There is nothing more pitiful than a high powered bird dog with nothing to do. We've all (hopefully) got one in the kennel. The one you go to when bragging rights are on the line, when you've been driving for two days and the country opens up and it's time to put the main man on the ground. He's the MAC Daddy, the Cover Dog, the Big Dog.....and, now, he's out of a job. It's just too hot and humid, the training birds aren't available and the pasture is grown and full of ticks!
I still work my dogs every day. I road them in the morning (on very hot, humid weeks, even before light) and we play and do light yard work exercises in the evening. When I take my evening 2.5 mile walk, one of the dogs goes with me so we can practice working together. Of course, to them the evening walk is just a boondoggle with me interrupting every so often. I think this type of work is important to a dog- they can remember it's a team effort.
I use the Dog Den 2 in my kennels. With the door up and the insulation all around, the inside of the kennel stays cool. I often enter the barn to find them in the Dog Dens with paws and heads lying on the lip.
I change the water daily in the bowl. That will keep it clean and cool. Bacteria will grow in the water bucket and cause problems with the health of the dogs. So, I dump and refresh the water every day, and dump and clean with bleach and refresh once per week.
On really hot days and nights, have an oscillating fan blowing over the kennel. They seem to enjoy that, as well.
One thing I do not have is a water-mister. With the high humidity, I've always been dubious at the efficiency of the unit. Other kennel owners, even here in the South, swear by them. I may take a look at what they are doing.
I guess the bottom line is to keep them occupied, cool and well-hydrated....and have opening day marked on the calendar!