I would suggest a taller tank, with a vine/branchy setup. Although not normally a tree climber, in captivity, if the heat is higher, giving greater temprature seporation, they will easily learn to climb. This will also reduce medical issues associated with resting on soiled tank floors. In the end, you might concider a full wood cage with a plexiglass, or glass door in front. Line the walls with thick black plastic, caulked in place, and use a cement mixing tub as the bottom. (Removable and replaceable). The wooden structure will retain heat better, and the plastic walls will allow you to spray the cage clean. The glass door will allow you a more desirable access to the snake cage.
You can even go so far as to buy a prefab bathroom sink counter, or a cheap entertainment center for about $30 - $50, Entertainment centers already have glass doors. Just put a scrap piece of wood on the back, attach your plastic liner to it, cut a hole for the light, and another hole for the bottom tray. My iguana is getting a similar setup, but with a cheap standing shower stall as the base and walls. (It won't look like a shower when I get done with it!