The tub of the camper is simply plywood standing on end, the floor screwed in from the perimeter.
The floor isn't rotten, just badly designed by KIT. It's a 1/2" sheet of plywood outer bottom with 1x2s on top making up an 1 1/2" structure with a ~3/4" particle board layer on the top. Particle board doesn't provide much strength to a truss and subsequently, anything past the end of the main 8' section of floor sags when it's used to hold the camper's weight.
When you lift the camper up, the floor straightens back out. Structurally, the floor should be supporting the over hang in addition to the 12' 1x3s that run the length of the camper in the walls.
I'd love to simply build a whole new frame built on a 2x2 size base instead of the 1x frame that the camper was originally built with, but my barn stall is only big enough to fit one camper in, plus getting new aluminum for the nose, roof, front and rear would be insanely expensive with today's metal prices (Camper would end up being wider because of the thicker framing members).
Inside, the only things anchored to the floor are the two cabinets in the dinette, the holding tank that hangs from it on the underside. All of the plumbing rides up on the wings except for the drain in the shower and the line going through the floor to the tank for the toilet (Single holding tank).
My main concern is the camper simply spreading wide once the floor is pulled, I know she'll mostly hold together given how much flexing the tub does right now because the floor isn't really doing anything to give it rigidity anymore.
The front and rear walls are a truss made with a plywood sandwich which gives them far more rigidity than the side walls, which is simply 1/8" thick paneling over a 1x2, 1x3 frame.
I originally thought about sistering the floor, but the placement of the holding tank, which I'm plotting to replace with a newer ABS RV tank and the alignment of the grey water plumbing under the over hanging floor makes it a no go.
If I pulled the 2x3s that run under the edge of the wings, I could probably drop the whole camper tub as one piece, its simply screwed in to the bottom of the 1x3's that run along the bottom edge of the wing walls.
