How do I prevent/remove surface rust caused by ocean air??

[VanCityWW]

My brother has a VW bus from the 60's, its in Hawaii, and always parked a few blocks from the ocean. The issue is that even though there's a car cover on it, and its in a covered car park, everything metal rusts. A lot. Even the painted parts of the bumpers and wheels get surface rust - it comes off pretty easy, but its pretty unnerving and we're worried about what we don't see. I've clayed and protected the paint before, but I'm wondering if there are other products and procedures we could employ? Will wax do a good job of protecting the areas that are getting surface rust? I've seen various deironizer and decontamination products , are they worth it and what should I get? Anything we can do to the undercarriage besides an undercoating?

thanks