I installed a $150 3.7 cubic-foot apartment-type compressor refrigerator in my 1967
International when I first bought it 20 years ago to replace the rotted-out original unit. It has operated very well.
When driving on the road, I power it from the tow-vehicle battery. To do this, I ran four 10-gauge wires (two positive, two negative, equivalent to 7 gauge) from the tow-vehicle batteries to the trailer battery. I have a connection plug between the tow vehicle and the trailer for this dedicated circuit, which is fused at the tow vehicle battery with a 30-amp dc fuse in each of the positive lines.
In the trailer, I have a $75 600 watt (1200 peak) inverter connected to the trailer battery. The refrigerator is plugged into this inverter, thus allowing it to run on 120v ac.
I installed an ammeter and an on/off switch in the tow vehicle to monitor and control the circuit while powering the refrigerator when towing. I have observed that the refrigerator takes about 12 amps when the compressor is running, and it cycles on and off like a normal refrigerator.
Even though I don't boondock, if I did I would get another battery or two to run the refrigerator with the inverter while parked, and recharge the battery(s) with my quite, little 1000-watt Honda generator during the day as needed.
The refrigerator is rated at 1.05 amps ac, which equates to about 10.5 amps dc.
There are lots of ways to skin a cat. A Boy Scout can do them all.