In Hawaii corrosion, especially on aluminum, is a constant war. The air is full of salt and the humidity is high.
Corrosion is terrible.
Various solutions have been tried such as hosing down a new beam with WD40 before putting it up. Particularly troublesome are sliding, nesting aluminum tubes on beams and verticals. In my experience, the more noxious and offensive a substance is to work with, the better it protects. An example is Aqua Lube, a substance that comes in a can like a paint can, has a consistency of melted green chewing gum, and seems to crawl up your arms like some living goop out of a Science Fiction movie. It is extremely effective even in areas where it is subjected to salt spray.