Ammonia versus Compressor Fridge...

Any ammonia fridge manual will tell you to first pre-cool the interior by running the unit for 'x' number of hours and then to load the unit with pre-cooled food and the freezer with pre-frozen food because the fridge won't react (cool down) nearly as fast as a compressor fridge will, However, I still believe it takes less power to do the job and power consumption is everything when camping off grid with no hookups.

Though I have never owned one (and never seen one in operation) I see you can get an ammonia fridge with an ice maker installed. Not sure how that would work (with the recovery time) but they are offered.