WD-40 is not a lubricant. Stop using it on your chain.

Living in the tropics I understand what it is to get wet, really wet, far too often.

You can wipe your frame and external parts down with a coating of BIKE LUST or similar products. That will protect them a bit.

ALL threads MUST be greased. I would even put a super light coating of chain lube or grease on the BB30 axle and any other exposed metal parts. By this I mean putting some on a shop rag and giving everything a good rub.

Also, look at some penetrating oil. It can help with brake and der pivots and other places water can get in and you can't.