Have a look at this one. I'm digging it for the larger bathroom, and the "protected" stairwell to the outside, plus I like the center door.
Water is all on the drivers side, where the dump tanks will be as well as the water supply tank. Pass side will be "fuel", diesel tanks, propane, the interior stove, and an exterior gas grill pullout. Prob also have the generator behind the rear axle on the drivers side but it's exhaust will run out the rear or drivers side.
Question, where is the best place for a fresh water tank? I've seen some of them inside, and some under the bus.