I see. That means you have to be sure that the vent will work. Argosy trailers, I believe, all have a roof vent, not sure about motorhomes. It would help if you post the details of your rig.
Another thing to consider is the little 12 volt
fridges with the Danfoss compressor. The marine guys have been using them for around 15 years and they have a good track record. There are several manufacturers of fridges using this device. Here's the first one I found:
Amazon.com: 43 Qt Portable Compact Refrigerator Freezer - EdgeStar: Automotive
Dometic also makes them in a wide range of sizes:
COOLFREEZE SERIES - Dometic Compact Portable Refrigerator Freezers
You could add one of those to your rig keeping the existing fridge and that might work out as well for less money and effort.