Can a Barbarian stay in rage while polymorphed? [duplicate]

If a raging Barbarian gets polymorphed into a Tyrannosaurus Rex or a Mammoth or something, to give it more hp, does the rage drop? Polymorph says:

The creature is limited in the Actions it can perform by the Nature of its new form, and it can’t speak, cast Spells, or take any other action that requires hands or Speech.

The Barbarian has already taken the rage bonus action. Rage says the following:

Your rage lasts for 1 minute. It ends early if you are knocked unconscious or if your turn ends and you haven’t attacked a hostile creature since your last turn or taken damage since then. You can also end your rage on your turn as a bonus action.

This says nothing about the rage ending if you change shape. So would this work?

Would it break things to allow a Barbarian to cast spells in rage?

If I was to make a homebrew barbarian subclass that allows barbarians to cast spells in rage, or allowed a barbarian that multiclassed into a spellcasting class, would it break anything? It doesn’t seem that it would, because the no spells while raging mechanic has always struck me as mainly mechanic, but I could be wrong.

Does Rage Prevent Divine Smite?

I was reading both of them, and if you had a hypothetical Barbarian Paladin multiclass, would the use of divine smite be prevented by raging? Unlike other smites, it says that it expends a spell slot, but isn’t listed necessarily as a spell. It reads more like a special ability that just happens to cost a spell slot.

Divine Smite:

Starting at 2nd level, when you hit a creature with a melee weapon attack, you can expend one spell slot to deal radiant damage to the target, in addition to the weapon’s damage. The extra damage is 2d8 for a 1st-level spell slot, plus 1d8 for each spell level higher than 1st, to a maximum of 5d8. The damage increases by 1d8 if the target is an undead or a fiend.

Rage: (Relevant portion)

…If you are able to cast spells, you can’t cast them or concentrate on them while raging.

Can a raging barbarian carry live rabbits to kill them, in order to keep his rage going?

One of my players, a human barbarian, came up with the idea of carrying captured rabbits, feeding them and treating them nicely, so that he can rip them apart mid-battle if he knows he will be unable to attack during the round. Does this sound balanced or does this sound like breaking the rules?

Can a barbarian maintain rage by attacking a creature that is not present?

Suppose a raging barbarian does not see any opponents on the battlefield but is attempting to maintain rage by attacking a hostile creature, according to the following:

Your rage lasts for 1 minute. It ends early if you are knocked unconscious or if your turn ends and you haven’t attacked a hostile creature since your last turn or taken damage since then.

If there was a successfully Hidden opponent on the field, the barbarian would be permitted to attack it by guessing its location. Even if they were incorrect, that would be sufficient to maintain their rage.

But how far ‘off’ is the barbarian allowed to be in their guess and still have the attack count?

Suppose the successfully Hidden opponent has actually left the field without the barbarian knowing. Does the fact that the opponent is not actually there prevent the barbarian from making an attack on an unseen opponent?

If yes, and the rage ends, the player then gains information about the fact that the opponent is not present (which seems to go against the spirit of "If the target isn’t in the location you targeted, you automatically miss, but the DM typically just says that the attack missed, not whether you guessed the target’s location correctly.")

If no, and the barbarian is allowed to attack an opponent that is not actually there based on the plausible belief that an opponent is present, then what prevents the barbarian from postulating an opponent who could be there? For example, the barbarian invokes an NPC that has successfully Hidden against the party before – is it enough to maintain rage for the barbarian to say that they believe said NPC is present and Hidden and then attempt to attack them as an Unseen opponent?

Somewhat related: A barbarian’s belief that they are attacking an opponent is not sufficient to maintain rage if what they are attacking is an illusion. So attacking a not-creature that is there is not enough to maintain rage, but is it enough to attack an actual creature that is not there?

Are Vengeful Ancestors’ damage-dealing reactions enough to sustain the Barbarian’s rage?

To sustain their rage at the end of their turn, a Barbarian must have attacked a hostile creature since their last turn or must have taken damage since then. [PHB, pg. 48]

In the level 14 feature of the Primal Path of the Ancestral Guardian, "Vengeful Ancestors," the spirits called by the Barbarian’s rage may do force damage to a hostile creature. Mechanically, the Barbarian is using their reaction to cause this damage. [XGtE, pg. 10]

Is the fact that the Barbarian is using their reaction to cause damage to a hostile creature enough to sustain their rage? Or is this insufficient because the damage is not being caused directly by the Barbarian?

Any way to cast dragonmark SLAs in a rage?

Pretty obvious dual to this question, but now for (dragonmark) spell-like abilities.

While raging, a barbarian cannot use any Charisma-, Dexterity-, or Intelligence-based skills (except for Balance, Escape Artist, Intimidate, and Ride), the Concentration skill, or any abilities that require patience or concentration, nor can he cast spells or activate magic items that require a command word, a spell trigger (such as a wand), or spell completion (such as a scroll) to function.

Spell-like abilities require concentration, though obnoxiously they don’t just come out and say it. Instead we have this:

Spell-like Abilities

[…] In all other ways, a spell-like ability functions just like a spell: […] It is possible to make a Concentration check to use a spell-like ability defensively and avoid provoking an attack of opportunity. A spell-like ability can be disrupted just as a spell can be.

The spell-disruption mechanics are all about your concentration on the spell being disrupted, with Concentration checks made to maintain your concentration and complete the spell despite the disruption.

Dragonmarks are feats that grant spell-like abilities, and since there are a number of feats that tie dragonmarks in with action points and those are something my rage-cycling build has in great quantity, being able to cast them while raging would be very effective.

There’s an argument to be made that rage also says “He can use any feat he has except Combat Expertise, item creation feats, and metamagic feats,” immediately after the first quote above, so you can use spell-like abilities from feats. But dragonmark feats aren’t themselves spell-like; they just have the effect of granting a spell-like ability. That is, I might buy this if the dragonmarks said “This feat is a spell-like ability,” but instead they say “You gain the use of […] one spell-like ability.” So I consider this dubious, and for the purposes of this question we’ll assume the DM doesn’t go for it.

Righteous Wrath is another one that sounds like it might help but then probably doesn’t: though it says “While raging, you retain clarity of mind unusual among barbarians,” it doesn’t go on to describe that how far that goes—and the examples it gives are all things barbarians never had any problem with in the first place. There’s no suggestion that it goes as far as allowing spell-like abilities—and at least one prestige class that requires Righteous Wrath has “You can cast this class’s spells while raging” as a specific class feature, so we can be pretty sure it doesn’t go as far as allowing spellcasting.

Finally, there’s the rage mage’s spell rage and the Rage Casting feat, which allow casting spells under certain conditions. Spell-like abilities are not spells, however, and it’s not at all clear that those features should apply here. Normally we would expect spell-like abilities to be separately listed if they were to be included. The description of spell-like abilities does say “In all other ways, a spell-like ability functions just like a spell,” but in reality this is a problematic description because there are so many ways in which spell-like abilities don’t function like spells. (It would be more accurate to say that a particular spell-like ability functions quite like the spell that it is “like,” excepting that it’s a spell-like ability with all the differences that entails.) In any event, the restrictions on both spell rage and Rage Casting make them really poor choices for my goals.

So, without making assumptions about these things being interpreted generously, does anyone know of a way to activate a (dragonmark) spell-like ability while raging? Tricks to exit the rage and re-enter it are not answers; I want to cast the spell-like ability while raging.

E6 is preferred; Epic is not allowed at all. Otherwise, any Wizards-of-the-Coast-published 3.5e materials, as well as 3.5e issues of Dragon and Dungeon, are acceptable. Third-party material, regardless of its licensing status, and homebrew material, regardless of its quality, are not acceptable (I am already aware of options that fit the bill from those categories; the point of this question is to avoid that). The form of the option doesn’t matter: feat, class feature, magic item, spell, whatever. I’d prefer not to have to multiclass for it but if that’s a way to do it, I want to know.

I’m not really looking for shenanigans; I’m hoping to find something that just says “you can use spell-like abilities in a rage,” or “you can use dragonmarks in a rage,” or something. I guess there could also be “you can concentrate in a rage” would probably get us there, or get us there in combination with forms of spellcasting during a rage, but I’d want to see the case pretty fleshed out for that because it gets into the weeds a bit.

I may accept RAW shenanigans, but only if they’re particularly air-tight and require neither DM assistance out-of-character, nor NPC assistance in-character. In short, please avoid anything that starts going “ask your DM to accept this dubious interpretation that might be there, if you squint.” Greater uses of wish and stuff like that are right out.