I agree, go back with the colors that were there prior. You seem wide open for suggestions on doing it on the cheap, so here it goes. Eastwood and others make a bunch of coatings to convert/ cover rust pretty well. You can also use a grinder/ wire brush wheel in a drill to get to metal and remove light rust then coat with an etching primer. If you are not real worried about perfection- take that drill and wire wheel and get what you can underneath then rattle can some undercoating.

FOr any holes that are good size, rivet some aluminum or tin in and then fiberglass it in.

For the panels that show- take your time on any body work and do lots of blocking and sanding to smooth the surface as best as possible, and I would look for someone who will paint on the side at your place for a way less rate than a shop. There are guys out there- you just got to look. If you cant find someone, get on a paint forum and start asking questions- guys are willing to give advice. Practice on junk then paint it yourself- doesn't have to be perfect on a low budget!

Sounds like you got some energy there so get going on it