In the Pacific Northwest, I don't often wish for air conditioning and am not always hooked up. I tried a mini cooler in a dryer climate (for the dog child) that fits on my little shelf. It really didn't do a thing, so if anyone knows of one that does better, do tell, please. Turning on the ceiling fan doesn't do a whole lot when it's hot, but with it and a battery operated fan, it was more comfortable at least, and a wet towel in front of the fan helps, although not much room for such. Luckily, I don't camp much in July or August.
My Coleman Xtreme cooler, 50 quart, didn't do too bad for being in the hot sun for three days. I cooled it some, placed two frozen gallons of water in there plus half of my bottled waters were frozen, put the food in, dumped ten pounds of ice chunks on top, got home, and still had some ice. I kept a wet, white towel over it at the campground. I don't purchase a rotomold type because it won't fit where I need it to be. I don't know what I'd do if I wasn't close to ice to replenish on a longer trip. One time, I took, in addition, a 70 quart and made it five days with the addition of ice once. The 50 quart fits on the front of the trailer alongside the truck box. I don't have room to haul foil bubble wrap.
Any new ideas are appreciated. I don't want things that run down my battery. Usually, I'm in mostly shade, so sold my solar panels.