There are absorption refrigerators which operate like traditional RV refrigerators (run by heat), but work only on electricity - not propane. These are extremely rare, although sometimes used in hotel rooms and dorm rooms because they are quiet. Because they don't burn fuel they can (and do) exhaust heat within the room. That would address the outside vent issue, but there are so many other problems with this design that I certainly wouldn't want it.
If I had a trailer prepared for a compressor-type refrigerator, there is no chance that I would vent it to the outside. The heat being pumped out a refrigerator is mostly heat that came into it from the trailer interior anyway, so very little would actually be added to the interior. An outside-vented refrigerator is a very small air conditioner - because it does pump heat out - but that slight benefit would not be worth having the vents to me. If it is so hot outside that the refrigerator heat is an issue, an outside-vented refrigerator is going to struggle anyway, since it is pumping heat up such a big thermal gradient.