The "burningman bucket design evap cooler" is not designed for indoor use, you have to place the bucket outside and duct the air in your vehicule. It works but not practical for in-car/van use, and can not be used in a moving vehicle. My first evap cooler was based off the bucket design, but after I dropped water all over my vans carpet I had to redesign it. If its a hot day, the bucket design is better then nothing, the cool air feels good. You just have to empty the water out before driving somewhere, and emptying the water can sometimes wind up on your floor.
The blue "durakool" evap material used also gets clogged with water impurities after about 3 months of use and restricts airflow. I stopped using it, The aspen evap material drops too much small particles that will eventually clogged the pumps and is harder to work with. The evap material that works good is the celdek evap pad, last up to 5 years without getting clogged.
As long as the humidity isn't too high, swampcoolers work great, I been using them for years. I got a small one running right now on the low setting keeping me cool, using less then 1 amp of power. On high it uses about 2.5 amps. Over the weekend which was cloudy but still got warm, I only had to add 1 gallon of water for both days, on a hot day it might use a gallon a day.
But you always want to improve on it, the air/water heat exchanger we been testing is a small improvement that will reduce the temp another few degrees. Even if its just 3 degrees, I'll take it. I just have to figure out where to put it in the limited space available.
A design like this would work better in a vehicle, the water is isolated below the evap pad, so it doesnt come out of the cooler while driving. I use 4 inch flex ducting to bring the outside air into the cooler. 120mm computer cooling fans are small enough and move enough air at 12 volts.
celdek evap pad, last 5 years without getting clogged, and I used them that long.