Google any brand of vintage fiberglass trailer. "floor rotten Scamp", "floor rotten UHaul". "floor rotten Burro", and so on. You will see a lot of threads on every brand.
Trailers not routinely maintained, and in particular, ones stored outside, will get leaks
. Water tends to leak into the trailer. This water eventually finds the wood in the floor and rots it out over time. Burro has an unusual leak source from the outside, around wheel wells.
My strategy is 1) inspect floor carefully to avoid rotten floors, 2) proactively do maintenance on leak sources, and 3) store inside when not in use. I find most people do not maintain their stuff. Instead, they use until the item fails. Leaks
in trailers can go unnoticed for years. If someone camps 40 days a year, that's a lot! But it also means the trailer is stored for the over 325 days! So how it is stored is important!
I looked at several vintage FG trailers with rotten floors. I passed on them. Where I could see the wood floor, I inspected that as well (under dinette, under gaucho, under refrigerator). I looked at one that had STANDING WATER in one of the dinette benches! And of course, seller described it as having no leaks
. OK, sure, right... Hopefully I did OK.
Become an expert on the brand you want, by googling problems and contacting some forum "experts". I think its better to look at ONE or two brands, easier to become an "expert" on one, than on a dozen.
I am amazed at some of the projects members have taken on here. They have my full respect! I'm up for a project, but not a complete gut.