We have a 20 gallon tank, we haven't measured her but she is a little over a foot I'd guess. We have a hydrometer in the dead center of the back wall and a temperature gauge on her warm side of the cage, she has a little tree that she can climb and also hide under ontop of her heating pad, close by to that is her water bowl, her heating lamp is above both of those. The center of the cage just has a little skull prop from the pet store that she will crawl through every once in a while, and then on the far cool side is her basic log hide. The substrate we use is some aspen substrate marketed for hamsters (I've read there isn't a difference between the ones marketed towards snakes aside from the price, so we buy the hamster one. If there is a difference please let us know!) We keep a damp towel on top of the wire top to the cage to keep the humidity in and we mist the tank with a spray bottle full of water every hour or so.
Also I heard moss could risk giving her scale rot from being too humid? Is this true?
Here's a crappy picture of it: http://i.imgur.com/f7ndWCN.jpg?1