I know that Jean-L has replaced part if not all of his floor in his boler
American. They were built very similar to your Love Bug
. I've sent him an email asking him if will post how he did his in this thread. That is if what he did applies to your situation.
My guess is that you are going to have to drop your frame. I'm not sure how much you are going to have to take out to do that. Scamps also have wood floors so that might be worth a search. If I were to do mine, I would make 4 braces that would support the body by the belly band at the sides by each corner. Jack the trailer up by the frame, place the braces, remove the bolts and screws that hold the body to the frame, then drop the frame and remove it. (I composed this post while Robert was posting his. Just a different point of view, both will work. Keep in mind that the curbside fiberglass is slanted down.)
I would then replace the floor. I'm not sure if I would use plywood or not. If so, I would be tempted to go for marine plywood. I've also seen engineered panels that are fiberglass on both sides with a honey comb lattice in the middle. They were used on the Oxygen
. It appears that 3M owns the company now, but here is some info.
They would be my first choice, depending on price and availability.