Although I weld my panels now I did rivet and sheetmetal screw patches on in the past when I didn't know how to weld. With great success too. If you go that route my suggestion is to use a chopped or milled fiberglass product to seal the seam. From both sides if possible. It will make the repair waterproof. You can use body filler to make it look pretty after that. Many of my rivet jobs lasted 15-20 years done this way.
Good luck,
Keith
