not phil, but i ran dual batteries for a long time afraid that i needed the juice, but a guy i run with has run his fridge off a single group 31 for years with no issues and he sometimes camps for a couple days before firing up his rig.DO you keep it plugged in overnight or keep it off and it holds its temp? .
i got in the habit of the last few hours i was driving, i'd crank the temperture up, then turn it back down when i park. that way the stuff gets into freezing temps while the rig is running and the fridge doesn't have to be set to a low temp when parked overnight so it cycles on less. if the fridge isn't packed full, a towel over what's in there helps too.