Mount that circuit breaker on the side of your battery box, clip the cable headed to the cut off switch and put a couple ends on. Looks like you have enough cable to get that done. @SpeedThrills
Be careful with what you buy for the amp rating on those breakers. That says it's 12-48VDC. 12 volts and 60 amps is MUCH different energy than 48 volts and 60 amps. Make sure you size the breaker to the 12 volt rating as the 60 unit will not likely ever trip unless you started welding with your 1/0 cable up front. IIRC some of those 60 amp breakers are at 200+ amps on a 12 volt system.
Appreciate the positive feedback from folks regarding my approach and help. Thanks!