[peggus]

Don't worry about the peak amps, size your protection components for continuous current. For the Curtis that's about 200-250A.
The 160V, 250A breaker on this page has been used successfully in many vehicles:
http://www.solarseller.com/dc_circuit_breakers__dc_circuit_breaker_ul_listed_to_125_volts_dc.htm

Thanks for the input. I looked at the Airpax and the largest I found is 250 amps.

I running 144 volts and 500 amps and haven't found any circuit breakers (or switches) that handle that much current at that voltage (DC) that doesn't cost a fortune.