Another option would to purchase a portable unit, some even stand upright VS like a cooler. Their temps are adjustable all the way down 0 some below... they are not cheap but we don't always use the camper sometimes we travel and having a cooler that can go into motel rooms and the truck is very handy...
portable frig/ freezer-Repo
05 Tundra 4x4
1977' Road Ranger, Diddums is in action.