I think that it will be safe provided that you do a few of additional things: 1- make sure that the refrigerator has the minimum amount of clearance specified in the instructions for the back, sides, top, etc, 2- Make sure that the electrical circuit/wire going to the refrigerator is adequate for the load, 3- Rig up a latch, bungee cord, etc, to keep the door closed when you are towing the trailer, 4- Lastly, if you are planning on running it from the batteries, make sure that you have an adequate sized inverter, it is fused properly, and the batteries have enough capacity. Don't forget that inverters are 80%-90% efficient.