Xist -- I thought about editorializing but just put the list up as found. They're listed, from 'Nothing' on, according to service life.
Concrete makes more sense for a house—or a canoe. Copal varnish is actually pretty rare. It's made out of amber or something. They must have had some to try; it only gave six month service life. I think 'resin-base paint' is like spray-on truckbed liner. It's described as flexible.
So my conclusion is that instead of messing with fiberglass, just spray out the inside with boiled linseed oil, and the outside with truck bed liner.
Maybe it will be time to bump the
Military Theme thread.