UPDATE:
Hmmmm…..OK... mixed results. Like I said, this is an experiment.
The Dometic CC40 chiller box works well...except when the interior ambient temps reached about 100 on a couple of days, and the box set to 5f was climbing to about 12f...my ice cream bars were soft! The published specs DO say that 90 or above temps and the freezer will not maintain the minimums. So there is nothing wrong with it, it is just not an extreme performance unit.
The ice stayed mostly solid, if a bit slippery, and the meat items stayed frozen...
The main issue for me has been power consumption. Yep, it runs off one 100w solar panel, with associated controller and battery, BUT...I had to keep moving this portable panel, or run it off my other power system and run the generator to assist that system recover in the morning or after a day of cloudy weather. That little 12v compressor runs a LOT with the unit set to 5 degrees...often more than 75% duty cycle...if set to about 40f it would obviously run less often.
But after about 2 weeks I had finally used most of the frozen food and simply reinstalled the freezer bulkhead in my r-pod Dometic built-in absorption unit, transferred all the perishables into that, and now the 12v fridge box is being used as an expensive dry-box/pantry.
I had previously added a condenser fan in the upper vent opening of the built in, and was using the built-in fridge as a fridge ONLY...so propane use was probably minimal. How minimal?
Well today I had a propane supplier here in Cheyenne WY top off the 30 pounder.
3.3 gallons of LP used in about 3 solid weeks of boondocking. Mostly warm temps....in and out of the fridge several times a day, cooling warm cans of soda, and of course some of that propane use was for cooking...usually one or two meals per day, sometimes also heating water for coffee, and several warm showers for myself and a couple of warmish showers for my pooch.
If I had a LOT more solar, the 12v compressor fridge would make sense, especially if boondocking out in the cool desert in the winter, far away from convenient sources of re-supply.
But for more normal use, for just me, I think I will try to rely on the propane-fired Dometic for my usual 2-4 week excursions.
{edited for clarity and supplemental info}