I'm living in Florida as well, and I know exactly how fast metal flash rusts here... about 10 minutes. Here is how I dealt with it. I would get the panels back from the blaster, I would lightly spray some Phosphoric acid and wipe it off real fast, don't let it dry. This would keep the panel rust free for a day or two. I would then sand the panel and clean it really well with PRE or other silicone/grease remover. Then hit it with epoxy.
There are plenty of rust inhibitors out there that are probably better, but cost more.
Another trick is to bring the panel in the house. The A/C actually takes moisture out of the air. Just have to have an understanding wife... which is why I know about the phosphoric acid!
