I think to do a good job you are going to have to gut the inside, I would assume the engine mounts and other interior pieces have the raised floor sandwiched to the stringers/hull...

Any pics of the interior???

I wouldn't give up on the idea of replacing the floors but I think your going to have to give yourself at least a few months, maybe a winter project???

It's hard to believe when you look at some of the balsa and wood floors in the boats but it essentially has a THICK layer of glass/resin over the wood and that has to give MUCHO strength to a flat or hydro...

A well done floor has virtually no sign of having a thick layer of glass over the wood floor... Your boat may not need that kind of strength but if you want a slick / good looking floor that will not have checks/cracks all through the resin it's going to have to have a substantial amount of glass buried in there...

Also, just resin alone with no urethane clear over the poly resin will start to turn yellow in a matter of years if it is left in the sun for very long... The resin alone without the glass is not very strong, like a cement driveway/street without steel in it, it will crack up... Add the fiberglass and it becomes some tough shiiiiiiiiiiiiiiiat...