I took a different approach in my own 4106, although my floor was probably in somewhat better shape than shown in your pictures.
You may notice on examination that the floor extends under the sidewalls on both sides of the coach. I don't know how it could be removed, but it could be cut off and a new piece butted up against the remaining part. I chose to leave the original floor in place, but cut out a few bad areas which I replaced with new marine grade plywood cut and fit to each repair. These were bolted in where applicable and the unsupported edges were attached with a backer piece of the same material, lots of glue and screws.
The seat rails on the wall are bolted to the ribs and can be removed easily. As for those in the floor - don't even try to remove them. I took a heavy duty router (a milling tool would work better) and shaved them down to the floor level. I think it was only about a quarter to three eights of an inch that had to be removed - and it went well.
Finally, after sealing the old floor as needed I let it dry well, then covered it over with waterproof paper, followed by a new 1/2" marine plywood and a lot of 1-1/4" drywall screws.
This method may not work for you if you turn out to be a half inch too tall, but it worked for me, and saved me a heap of work.
tg