For 250 to 300 ampere you need to put up a huge battery bank
haha.. Why don't you get a massage chair in your car and set it on rocker mode? Just joking..
Circuit breaker is a good option, provided you install a distribution block, and cables in proper configuration. Usually amps have their own protection (high low voltage, wrong polarity, thermal, short circuit), so its not a big problem.
Run zero gauge in your engine bay(big3), and to the capacitor/distribution unit. Further to amps if the distance is less you can either use 8 or 4awg (consult attached chart). I guess in case of a short circuit, the breaker would trip, no matter if its closer to the cap or the battery, and everything would be saved. Correct me if i am wrong.
Cheers!
