Is a full melee combatant party for Rise of the Runelords viable?

So I’m a DM with a bit of previous experience who discovered the wonderful world of Pathfinder Adventure Guides, and decided to try my first campaign of those with the classic Rise of the Runelords to see how fun they can be.

I’ve gathered three players who made the following characters: A Magus of the Mindblade archetype, a Paladin, and a Valkyrie player (from a third party publishing, essentially a tier-3 full BAB combatant). They are all level 1, and about to start the Burnt Offerings adventure.

I want to give them the freedom of choice to play whatever characters they want to play, and I could allow them to recruit NPC from the or even add in a support NPC to make up a fourth party member and therefore give them whatever support they need, but reading some feedback from people who played the module got me worried.

Is the module forgiving enough for they to be able to clear it with this party make-up? Am I going to have to create a supporting NPC? If so, what sort of support would be best to be focused on to allow them to deal with the campaign on the long term?