I am restoring a vintage fiberglass weirdo-pop up. There are threads in the vintage and the restoration forums. Pic of it is my profile pic. The floor is super solid. I found only one super small area of rot at the rear right corner. The area is about 8x3"...not even a full square foot. It does not seem to affect the structural integrity of the popup, and will not be an area where anyone will walk. (it's in a little storage area under a bench). The lift mechanism does not "push" off the floor like a typical PUP. It's a spring loaded device, so nothing is pushing against the wood. What would you do? Try to cut it out and patch a new piece of wood, or fill it with that epoxy/wood repair stuff...I forget the name.