The Stygian Gambit with three players

I'm putting together a group of players to try running The Stygian Gambit, which will be the first time for me as a DM. So far it seems I can get three players, but it's been tricky finding any more. For those who have run that chapter, would it at all be doable with that number? Do you have any possible rebalancing suggestions, or would it work to include a sidekick that can help out?