I should have made it clear that our freezer box is located in the aft cabin -- approximately 10' away from the fridge box which, of course, is in the galley. In this situation, the tech person advised against trying to run two evaporators off a single compressor. He said that it could be done, but we would not be happy. This was how our old Grunert system was set up and it seemed to work OK right up until it died. It did, however, draw a LOT of amps (i.e. 30) and, near the end, ran almost constantly. I suspect it ran out of refrigerant.
Yes, I understand that your approach of dividing one box into two zones, fridge and freezer, is very commonly done and we may well opt to do that later on.