I live in San Diego too. There are upholstery shops down there that do very nice work. If you need body and paint work, I wouldn't go to Tijuana, the quality is abysmal.
You might want to try spraying Body Protection Wax, or Cavity Wax, inside the panels. This won't stop what is already there, but it will help prevent further corrosion. I like products from Wurth- theirs comes as Body Protection Wax Transparent 33.8 Fl Oz, which requires a Wurth sprayer, or, the...