Disconnecting the Trailer Connection when staying Overnight.

I have a 2015 2500hd chev . When I had the truck camper on and overnighting on a back road in alaska ,I kinda forgot to turn fridge from 12v to gas one night ,by 3am I had camper battery and truck battery dead...(propane sniffer sporadically beeping).
Truck live line still live in this truck. I disconnect nightly after that night.
Luckily a pickup was driving by when I need a boost.