On my older trucks I drilled a hole in bumper or hitch somewhere and put in a 7/16 or 3/8 stainless bolt in it which I would clamp my ground from the winch to. With a power cable ran under the truck to the battery....running a 8000# Ramsey winch.
I just bought this 2020 2500hd last week and was more confused about where to hook the positive up. In my older trucks I had heavy 2/0 cable ran under the truck that had a clamp on it, I would connect to the battery. When I popped the battery cover, all my cables as I have them wouldn't be able to connect.
I haven't started to explore where to mount my ground cable off the winch.....