Originally Posted by SimonCh
Well what can I say!? I've always been one for functionality over aesthetics!
The suggestions Dirk makes though are about maintaining functionality / reliability.
If they are "critical systems" then the fact they have failed already means you are not ticking the functional box either.
At the least I would be making sure that I knew how to "debug" the system, and work around your most likely failures. If it took you a while to work out that fuses in that state were likely the problem then I think I'd opt for the "make it bomb proof" approach rather than "it will do and I'll fix it when I need to". At the very least make sure you know how to start the engine without the battery - as if the fuses are getting that corroded the isolator switch probably will one day too.
PS. My own electrics aren't much better - but I have backups for everything and a pull start on the engine, and I installed them all as a "quicky to test them" 4 or 5 yrs ago and they are still working - I may be about to replace the battery etc so will do all the wiring at the same time.