The first gens originally came with just one battery. I have run my 95 on one battery for a short time when the other exploded. You have to make sure that you don't short out any connections where the battery is missing.
The problem I see is that you need proper voltage for all of the computer related electronics at start up as well as power to the starter to start the truck. While I'm sure the truck would start, I am leery of the potential damage that could happen to your electronics.