You could get a Viper Gecko [SIZE=-1](Teratolepis fasciata), African Fat-tailed (Hemitheconyx caudinunctus), or even a Texas Banded Gecko [/SIZE][SIZE=-1](Coleonyx brevis) to name a few.[/SIZE]
lepord geckos and african geckos don't really thrive with sand though due to digestive issuses. <sand compaction> i recomend a breeding pack of viper geckos. 7 would be perfect for a 20 g long in a sandy desert like tank as they stay relativley small
I don't think there is a single reptile that would do their best in sand in captivity, when the are safer alternatives for almost any of them. So substrate compaction is a big issue for every herptile. Although by desert, I think what the OP was actually referring to the climate zone, and not the actual geographical habitats.