Great topic. My fridge stays cold while on. I have a thermometer and it stays around 38. Short trips I cool it down load it with cold stuff than keep all that closed up and running for about 24 hours before we leave. Then shut it down when we leave. Most trips are 1-3 hrs so I keep the gas off. It's a constant battle with myself to run with the fridge on. I'm afraid my tt will explode or if we wreck the tt will have broken open gas line etc.
I really like your idea. We recently drove 8 hours in 100 temps and I simply used two ice chests in the back of the truck.