................multi laminate plywood (8 or 9 ply construction grade) is cheap at Home Depot.........cut your floor........brush on three coats of 'West Systems' Epoxy,......making sure to do the end grain and the grain inside any holes.......Google... Gougeon Brothers or West Systems,..for the trick way to attach your floor.......check your stringers closely for any signs of rot...........West Systems has been the salvation of wood problems in big boats for years.........If you know someone with port supply discount at 'West Marine' stores........your material cost will be greatly reduced..........Epoxy sticks to polyester resin(fiberglass)but not visa/ versa.......sounds like composites are the wave of the future?............