Wow! This is a great question. I don't have an answer, but it almost has to come out of the "housing" inside the trailer, and then, it has to come out the door. I cannot see any way it could be removed from the outside (at least on my trailer). And, the concept of lifting off the top half of the trailer to replace a refrigerator seems way too much.
I'd start by removing any "front panels" and see what you find. I bet it will fit through the door, but you may need a friend outside to "catch it". Still, it can't be TOO heavy.
Hi-Lo 1707T - Tire Minder TPMS on Tow Vehicle and Trailer, 200W Solar Battery Charger
2014 F150 Platinum 4x4 3.5L EcoBoost SCrew