I used the Swamp Cooler at a Dock Dogs event. It was easy to keep it wet with the pool right there. I found that it dries out very fast in the Texas sun/heat and requires frequent re-wetting. So it is a good tool for the backyard but not for a hike/walk where it would be problematic to have sufficient water to keep it soaked.
If I was to do this all over, I would probably try the Chilly Buddy. I still might bite the bullet and get it to replace the Swamp Cooler.