Driver Guide:

check out this guys kits. Check out all of his kits (there's lots of them. Looks similar to what you're wanting... though the inputs are way different.

Man... you are making me want to get into rallying more and more. I never even thought about the fact that it could be a great (couple) activity with the navigator and driver! =]

Back to electronics... this looks like a fabulous idea. I wonder if you could actually use an empeg somewhere in the chain?