May want to consider a residential fridge that would fit in the space. The area already has a 120-volt outlet there that you could change the power source to an inverter. If you all your time in shore power or generator a inverter and a good battery will carry you between hook ups. Fridge will be much cheaper, and you will not have to run a heavy gauge wire for a 12-volt unit.
I have a 120 unit in my cabin that runs off an inverter, battery and solar, have had propane in campers for years and just got a camper with a 12 volt. The new camper has 2 group 31 batteries charged by 2 190-watt solar panels anthe fridge has been running in the driveway for 6 days now.
In your case I would probably put in a propane unit. No changing wiring or running new stuff. Just install and go.