I would use a fuse. Resettable circuit breakers are notorious for tripping for no reason. I had to take a 30A breaker out of my air pump circuit in my motorhome because it would trip at random and and the bags would leak down as a result. I replaced it with a fuse and it hasn't blown once.
Another anecdotal story: I added a 2nd battery in the trunk of my limo to power the A/V systems. I installed a solenoid to isolate the batteries which required running some fat cable from the trunk to the partition where the 2 battery systems came together. I, too, was afraid of a short given the long run. I installed a 200 amp fuse much like time2roll posted about a foot from the battery. It worked great.
