HELP first time buyer! Buldge in fiberglass exterior wall

I owned a ReXhall Aerbus of that same year. The bulge you describe sounds like delamination. If so, that is unusual for the Rexhall line of motorhomes. They are generally very well built with steel framing, not wood like so many others.

If it is a delamination, the value of the coach drops significantly.
Many would not even consider buying since repairs to a delaminated wall are very difficult and very expensive.

You might want to have the RV inspected by a professional. He can tell you the straight story.