I also miss the three way refrigerators. I don't see them being installed anymore in new SOB units either. I guess it had a lot to do with the draw on the battery.
I used to travel with the 12 volt
side on in my old Hi-Lo. The only problem was occasionaly the feed in the Bargeman outlet would not be making good contact and I would get to my campsite with a dead battery....and guess what, if the battery was dead the top on the Hi-Lo wouldn't raise. I soon learned to turn on an inside light when I hooked up. If it brightened up upon connection to my tow vehicle, I knew I had a good connection.