Back in the 60s when living in Tempe AZ that was the way to go. The trick of keeping cool was how to vent-in the outside air.
Granted you could not get real lows temps goings but I would take a 10 degree drop in temperature any day...
I use to experiment back in my creekside tent camping back in those days with a car radiator or car heater fan using cool water from the creek being pumped thru the cores and dumped back into the creek. Then using a DC Fan blowing behind the radiator or heater cores into the tent... Surprisingly cool temps could be had...
In Arizona all of the air conditioners were roof mounted and were hugh with water circulating through the coils. Then you would close all of the outside windows except one or two on one end of the house just cracked open a tad. This was best sleeping of my life at night haha... Somehow you would figure out which outside windows to keep open and which to keep closed... The only bad thing I hated to do was climb up on the roof to change out the air filters. You had to fight off black widow spiders all the time... The old wives tail of only finding one black widow was false where we lived in the outskirts of Tempe AZ...
TurboKool came out with this model for RV's but I never looked into them. How to handle the water sounded like a bad thing for something like this...
AS Don is seeing the only DC Current to deal with is running the pump and the fans... No A/C compressor motors to deal with for sure...
Roy Ken