I replaced the 12v wires to the fridge with #6 wires going directly to a Battery Isolation Solenoid that is connected to the truck battery and is only on when the key is in the run position. The fridge is never connected to the camper battery.
When we turn the truck off I do have to switch to LP or AC to keep cooling but if I don't I won't end up with any dead batteries just warm food.I still charge the camper battery with the original charge wire thru the 7 pin plug and using the trucks OE battery isolator.Fridge wires run thru a 2 pin plug.