You can also try using water bowls with a smaller diameter. I've noticed that turning on a fan in the room can help too.
I wouldn't put too many holes in the tubs if you don't plan on using a space heater for the colder days. I received my rack in early January and when I set everything up, it was 94°F on the warm side and 68°F on the cool side so I had to go out and buy an oil filled heater before transfering my snakes to their new home. Needless to say, It was a very warm winter in my room![]()