Klutch,
My group of technicians did a lot of work on fancy and expensive boats for many years. That is over, but we learned a lot. One of the things we learned was to coat every exposed connection with silicon grease. You can buy silicon grease as "Di-electric" grease at auto parts and other stores. All greases are dielectric, but the silicon greases have zero film strength, so it won't interfere with contacts. While it let the contacts touch, it will also prevent incursion of corrosives and cover the exposed metal.
In this case, I would suggest you find some crocus cloth (extremely fine sanding cloth) and use it to polish what you can get to and then bed the fuses in a small glob of silicon grease. I do this on all the exterior lights of my own vehicles and never have to deal with them use a bulb (the few that remain) actually goes out.
Matt