Lots of naysayers here on the forum. Looks like your model is a "light weight" looking at the frame. The frame damage is severe...looks like it ripped in half! The patch looks decent but hard to tell from the pic. I would be sure that's solid before investing any time in a rebuild.
Also amazing that the roof and walls are dry considering how bad the floor is, did you find where the water is coming in?
So without outriggers on the frame, it's obvious why the wall is falling if the floor is gone. The fix is to jack up the wall while you re-frame the floor that runs under it. The 2x3 floor framing runs across the trailer frame side-to-side with a end piece (kind of like a sole plate) that runs under the edge of the wall.
Unfortunately you can't jack up under the wall where the new floor needs to go, and I wouldn't want to screw thru the filon, so I would look to take out a window or somehow get a ledge to jack against so you can raise the wall and take the pressure off. Once you tear into the floor you'll see what you're up against.
The good news is that you need to take everything out anyway, so you only have to invest a little more time to decide whether to fix or part out.
I just went through a similar experience with my truck camper, it was free but needed some work. You can follow the repair blog on the link in my signature. I was confident doing the work after doing major repairs twice to our 2008 Terry TT.
Glad you're making $$ flipping these things...I had to put a new fridge in this one, so I figure I'm about $4k into a 2002 unit that's worth $8k, so figuring my time I think I made about $0.10/hr this summer LOL. But that's not why I did it....I have a better-than-new really cool camper for a fraction of what a new one costs!
