test drill your stringers and transom. use a 5/16" drill, mark off 3/4" length. drill into the encapsulated wood of the stringers and the transom about 4" up from the bottom of the deck. if the wood shavings come out dry, light colored, and smell like fresh sawn wood, then you are good.
however if the shavings come out wet, dark and smelling of rotten mulch, then the structure of your boat is gone.
literally the last thing to rot on a fiberglass boat is the floor.
we are saying this to help you understand exactly how dangerous a boat is with soft spots in the floor, especially a houseboat
at a minimum, read thru link #14 in the hull restoration sticky.
https://forums.iboats.com/threads/how-tos-and-other-great-information.283508/