Very interesting problem.
Oil is a pretty good guard against salt. While this might seem a strange cure, how about coating your equipment with a thin coating of oil, like perhaps WD-40 inside in every cavity? Not having tested this myself, your results may vary. You will need make sure any parts like the fan are working afterwords. And abandon the optical drive and instead use a USB one that you keep most of the time in a sealed plastic box. I'm not sure if WD-40 contains any conductive ingredient, but I do know it is recommended to stop rust. Then wipe off the keyboard so you can use it without too much mess.
And WD-40 stinks, so perhaps some other thin oil would be better for that reason. You might have to kludge your own oil film sprayer by using a compressor and some sort of air-ator. What comes to mind is the air-filter-oiler that I use with my compressor to send a little oil into the air flow for my air powered tools.
Many years ago I flew out to New Jersey to fix a poly peptide synthesizer in a chemical research facility there. There were using a chemical called TFA, Tri Flouro something. It was corroding the gold conductors on our circuit boards. I was able to fix it but it soon failed again and soon the whole thing ended up in the dump.