Not knowing the extent of the damage I trusted a big name RV dealer here in south central NJ to do a repair to the bathroom floor in my Surveyor. Big mistake.
I didn't cut the flooring out but put a piece of 3/4 ply over the bad flooring. This I supported with 1 inch aluminum angle screwed into the cabinets and tub. This raised the floor +/- one inch. The problem I'm having is raising the toilet. I've managed to cross thread the new 'tail' piece.
If I can get another 2-3 years out of it I'll be satisfied. But I will never that RV dealer.