Closed-end blind rivets are commonly used in pressurized aircraft construction, but I'm not sure they'd be worth the cost -- Avex closed rivets are expensive -- for our trailers, which generally have plastic rivet covers and don't have to deal with variations in internal/external air pressure that would eventually loosen the rivet mandrel button. Here's what I do: when I use rivets instead of stainless-steel hardware I install standard aluminum blind rivets with rivet covers, use butyl tape between the rivet cover and
fiberglass trailer wall, and fill the rivet with hot-melt glue from my glue gun.