Best bet is to replace the hatch- good ones in California shouldn't be too hard to find, no? Rust can definitely be repaired though, and well, but leave it to the pro's, imo. Here in the midwest, nothing doesn't have rust somewhere, at 20+ years old, unless it was bubble wrapped and kept in the living room its whole life. I looked into a fiberglass hatch a couple years ago, but a igotaguy that found me a good one, so I didn't have to go that route. After you get a paintjob, you'll always want to watch for that first bubble, signaling the next one is coming up.