DWM NM

I am installing a 12000 lb electric winch on my 2020 Chev Silverado 3500 HD. The winch reportedly could draw up to 300 amps for a short time under maximum load. In looking at the battery distribution panel in the battery compartment i see a terminal marked 500 A. My winch came with a circuit breaker (rating unknown) that presumably would be in the 300 A range. i would like to run a battery lead off that 500 A terminal to my circuit breaker. There seems to be no other terminal rated above 200 A. Any comments on this idea would be appreciated. Also, I have not found any wiring information regarding the factory second battery and its purpose. I assume it is auxiliary for starting my big diesel. I would like to be able to use both batteries to run the winch when needed but, not risk ending up with both batteries dead and not being able to start my truck. Your thoughts are appreciated. Thanks, Don