Interesting about the newer Dometics too!
In our case the only time we are on electric for the fridge is at home prior to a trip getting the fridge cooled down to load up. It is gas only when away off grid as usual. So it is easy to now have that 120v lamp on to say if the 120v is not on. (extension cord out from house got kicked or whatever)
Thanks for the suggestions on lamps etc. Usually tell if all 120v lost by no microwave light, but you could just lose the fridge's circuit if that is GFCI for instance. Whatever, for each RV.