I have a 20 gallon Long screen topped exoterra that will be empty in the next few months and am looking for some suggestions for what kind of snake or lizard would be happy living in it permanently. I already know what bigger snakes and lizards I want down the road when I have a bigger reptile room so I really just want ideas for animals that can live comfortably in such a small enclosure for it's whole adulthood.

The exoterra housed my BP who is getting a tank upgrade to something that holds humidity better. The tank I'm looking to fill is usually around 25% humidity with a large water bowl and no misting/ wet towel and CAN get to 70 with a great deal of misting and wetting towels 2x/day. I'd like to find something that won't require more than daily wetting/ misting or will be fine with just a humid hide because I do travel on some weekends and getting a pet sitter in twice a day is a challenge.

Temperature is not an issue really but the tank is already heated for a gradient of high 70's cold side to mid 90's on the warm side. It has a thermostat so I can alter the temp if needed.

Temperament- I don't mind poor dispositions or flightiness but for lizards I'd prefer something that will not leap out of the cage and run out of reach during cage maintenance.

I'm looking for something that is a little less common or for the more experienced keeper- though I should say that I have 25 years experience with snakes but much less experience with lizards (I have worked with them but not owned them). The shows I go to are filled with leopard geckos, hognoses and Kenyan sand boas but I'm willing to research to find breeders for the right kind of animal. Cost is also not a real factor.