Though I've read that a few Lance trailers had composite roofs, I think the truck campers are tpo. Is yours? Here, we talk about molded fiberglass trailers, fiberglass all around.
However, you will find tips for the basic systems that we all share... furnace
, water systems, etc. No one I know of is "re-inventing the wheel" here. Most campers have a lot of third-party systems, no matter what the trailer or truck camper is made of.
You probably just won't get as many responses to truck camper questions on a molded fiberglass trailer website as you'd get elsewhere... Honestly.