I have repaired several scamp floors and a multimaster tool is the best tool to cut the floor from the side walls. I have a S16 now that I am working on that needs a complete floor change. If you cut out all the upper floor sections at one you will have no support for the lower part of the shell and you will have a mess to deal with.
You have four major upper floor sections that make up the upper floor. I would start at the rear and work foreward at replacing the upper sections. The lower floor can be replaced when you have one or both upper side sections out. The upper floor side sections overhang the inside of the frame making the lower floor hard to deal with when replacing and attaching the lower floor.
Lowes sells self tapping countersunk screws for attaching wood to metal to attach your new floor down to the frame. You also need to use a sealing adhesive between the floor and frame to prevent leaks
. Getting out the old screws in some cases may be next to impossible. It's best just to cut them off flush once you get up the old floor.
Also if you pull out the center lower floor section and both upper side floor sections at once, this will be an ideal time to replace the axel if needed. I also clean up and paint
the frame as I replace the floor sections.
Send me a P.M. with your phone number if you want more info.
One more note: The shell is also glassed to the frame arms around each side of the lower door.