I have (temporarily) installed a "dorm fridge" in my Scamp
, pending a new 12V compresser fridge maybe next year. I put it in the stock location so have the stock vents on the outside. Yes, normally these do not require venting, because it is assumed they have space under, over, and on the sides to vent. They do give off a certain amount of heat, that is what they do after all. Remove it from inside the box and expend it outside. I have it sealed off from the inside of the trailer and even with the outside venting when I put my hand on the fiberglass counter above the fridge (heat rises) it is very warm. I was very surprised to note this and do not think it is enough to worry about, but I would recommend leaving room for air flow into the trailer if no external venting is provided.
By the way, I went to a lot of trouble to make an aluminum plate that mounted to the top off-side hinge bracket holes and a pin to keep the door closed for travel. I worked so hard mounting and trimming the fridge I hate to swap it out for a new 12V one. But once I get my solar
system in the new refridgerator is next.