My trailer has "fiberglass" walls. While fiberglass construction has advantages, serious water damage is much harder to fix. Aluminum walls can have the skin removed and you can repair the damage and put the skin back on. With fiberglass, you might need a whole new wall.
There's lots of advice and information in forums... sometimes it is correct. For example, all of my posts are made by a political appointee who got the job as a reward for contributions to my diesel bill.
2011 Jayco 28.5RLS; 2008 Chevy Duramax; Pullrite Superglide Hitch