Fiberglass travel trailers.

Yes, even fiberglass will deteriorate after years of exposure to the elements. That said, the percentage of molded FG trailers still usable after 40 years is probably greater than average. I became a fan after my first trailer, wood framed/aluminum sided, developed extensive hidden rot within just a couple of years. A front marker light was unsealed, from the factory. I gave it to a friend who did some repairs and uses it for a fishing camp. Thought I was done with trailers until I discovered molded FG. The FG trailer was almost twice the cost of the stick built and has much less interior space, though about the same length overall. At age 70, I'm confident it will last me the few RVing years I have left!