I also have a Ram, power stays on all the time to camper.
I looked at the Blue Sea ACR but problem is when solar charger voltage comes up on either battery side of ACR, the ACR connects the 2 circuits together and you end up charging the truck batteries with your solar.
I looked at big relays but as a mechanic I have seen them fail.
I might take the approach of putting a switch on it somewhere, the cheapest place would be to put the switch in the cable between the truck and camper (no cutting either vehicles wire harness).
There really isn't that much current goes through that 16 gauge wire in the truck charging system so I doubt I would miss it. I did think of just cutting the 12v feed (once I get my solar on new camper) but what if I was to need it some day?
I am always worried about unplugging the camper to not drain the truck, but on the down side once I had to run to town with Wolf Creek loaded, and I forgot to plug in the harness. I drove around for a couple hours no brake lights because camper covered truck tail lights. so I need to do something so I can just leave it plugged in.