Dave, I solved this problem many years ago. I constructed a neat, swamp cooler using a 32 quart cooler chest and a couple 72mm computer cooling fans. The cooler chest is filled with block ice, then I covered the opening with a 1/8-inch thick piece of plywood with the two fans mounted at one end of the wood cover. I cut two holes about 3-inches in diameter at the other end of the plywood cover. The fans are powered by a small, 12-volt power supply that cost $10 on Amazon and the fans were $7 each on Amazon. Those little fans put out a lot of air, and in this case ice-cold air. The fans draw the air down through the two holes, which passes across the blocks of ice, then pushes the air directly at me using a couple pvc plastic elbows the same size as the fans. Worked like a charm, and was almost like playing in air conditioning, even on the hottest days. The blocks of ice lasted about 4 to 5 hours, which was longer than the job lasted.
I used the same setup on my boat until I got a generator to run my boat's AC unit. It cooled the entire cabin interior down to where it made for comfortable sleeping on a hot, humid summer night.
The above photo is the first prototype and a second fan was added later to improve cooling capacity. The fan only draws .04 amperes, which is next to nothing.
Good luck,
Gary