Pull the 12 volt fuses for the radio and smoke detector to eliminate some of the battery draw, you won't be using them while not there anyway. A problem I see would be if your fridge has a heater around the door to eliminate condensation. My older units had switches to turn that off but the Dometic in my 2012 has no switch and it is wired permanently on. Since I boondock some, I have disconnected that heater. I accessed it behind the fridge light/door switch assembly. Then test to see how long the battery(s) last.