Unless you want to sleep on the floor, you can only get 4 adults in a Front Bath or Front Kitchen model, so you need a Front Sleeper model.
When you get a FS model, you lose hauling capacity for quads. So you have to go bigger trailers, over 30'. My buddy has a FS2600 Weekend Warrior and he could never get 4 quads in his trailer. I on the other hand, have had 4 full size quads in my FS3000 and I can sleep 6 adults very easily.