I installed a RED indicator "lamp" on the cabinet for my 3-way Dometic. I've ran my Scamp battery
down TWICE by forgetting and leaving the fridge
on when we arrived home after a camping trip.
Now, we enter the Scamp
, we clearly SEE the red light and I know the fridge
is still on 12v!
Personally, I've never thought anything about the AC side. I DO place a digital wireless thermometer inside though. That's the "proof in the pudding".