Looking at some bus tubs online, like the kind they use in restaurants, and they look like they would work great. They are cheap, and can come in black or grey to offer the snake a lot of privacy. My only concern is that I'm not sure if the tops are completely flat, and if they would work in a rack system.

Like this.

http://www.webstaurantstore.com/20-x...0215205BK.html