Fuses, Circuit Breakers or nothing at all?

Put SOMETHING in there, and think as you lay everything out: What happens if I crash this thing and "this" wire right here shorts?

You might be trying to crawl out of the thing while it's starting to burn to the ground.

Use oversize wire. I don't remember the name, anymore, but Belden and other companies sell wire with flame resistant insulation, much much better than the thermoplastic crap you see. Fuse/ breaker it as close to the battery as you can get, and keep breakers / fuses away from heat in the engine compartment.