Re: Glastron floor repair. Need help.
Use fiberglass. Cut the rotten crap away preferably back to a stringer, but not to the other side of the stringer. Kind of like drywall repair if you have done that. Cut a piece of plywood the same thickness as the floor. Coat the backside and edges with some fiberglass resin. Put the panel in place. Drill and screw it in, some adhesive wont hurt either. I like the Bondo hair (or the finer one, i think its called glass or something) fiberglass for around the seams. Lay it on as smooth as possible to minimize grinding and sanding later. Once that hardens scuff that repair area and the old solid floor area till all the crud is gone and the new glass has some tooth. Cut a piece of fiberglass cloth that covers the whole area. Paint a layer of resin over the whe area the. Lay the cloth down. Coat the cloth and about an in h surrounding it with resin. The cloth will absorb it and become almost clear. Make sure you can't see the surface of the cloth through the surface of the resin, add. More resin in those areas.
Let it harden overnight then you can carpet over the top. It wi be rock solid.
WEAR GLOVES AND DO IT IN A WELL VENTATED AREA! AND WEAR A MASK WHE GRINDING OR SANDING
I am no pro, but that is how I do it, and it works.
I add fireproof spray foam under floor areas that will not be storage.