How do I properly ground my cabover camper battery bank?

Question

i have 2 batteries in parallel 200 amp hours in my cabover camper . i have an charge line from an isolator 15 feet in length 8 gauge wire. my camper is aluminum/wood build. camper sets on truck bed with thick plastic insert/liner. what is my best ground option and at what gauge if any do i need to run off my battery bank?

Answer 1

8 gauge to the frame of the truck