Here's what we did in Okinawa. We had the humidity and salt water air, but not the chemicals.

Used pledge a lot! And when we weren't going to use something for a period of time, be it car or bike, we'd use regular car wax on it, but not buff it off. Let the wax haze up and then leave it alone. Did a great job of protecting metals. You could literally watch that stuff rust out over there.