Someone that tells me this: "it’s fibreglass so won’t leak." is either delusional or a liar. I would guess the former.
The problem with delusional is that they may not do the appropriate maintenance since they have a trailer that "won't leak". So expect window and roof vent seals to need replacement.
I've never seen condensation stain a ceiling, but I guess its possible. More typically, its a leak.
Every penetration through the outside of the trailer is a potential leak source:
windows, vents, any rivets, any stuff attached (like an awning), etc.
Pictures I have seen of the
Captain trailer show a roof vent along with vertical seams on both sides. Take a ladder with you and inspect the roof, look at the age of the vent, and any temporary fixes like gobs of silicone around the vent.
It's not the end of the world, but
leaks = project, and price should reflect that. Replacement
windows for that trailer are hard to find, so make sure none are broken (windows come from Europe).
Unique design with what I believe is a four piece shell (may be three pieces). Typical eggs are two piece. Every piece has a seam/joint, and how it is constructed can lead to
leaks as well.
Finally, there is a lot of wood on the interior of this trailer: all cabinets, walls, ceiling, and more are wood. Whenever you have that much wood in a FG trailer, if you do have
leaks, you often will have a lot of rot to deal with. In comparison, brands where the interior is predominantly
fiberglass, at least the cabinets, ceilings and walls don't rot. Trailers like Bolers,
Scamp Standard, Trilliums, and Casitas just to name a few have mostly
fiberglass interior.
Scamp Deluxe,
Amerigo,
Surfside (which looks just like a
Trillium but has a wood interior), Playpac, and others have a wood interior.
And as Jon wisely points out below, watch out for soft floors. Also look inside cabinets and benches for possible floor rot.
All that being said, they are cool trailers!
My Solo Trillium
Scampy
Linear Mode
