Make your reservations NOW.
With several thousand people attending the festival (50,000 attended the last Sea Festival in SihanoukVille), rooms will be at a premium. Even the prices will be at a premium. Kep's 1,300 rooms will all be filled, and some people will be staying in Kampot or at the top of Bokor Mountain and going to the festival in the day.
Even after the festival, all of December and January 2014, rooms will be pretty much filled.
Check out Kep's Hotels for a complete listing.