The only tidbit I can add to your regimen is to make certain that the sand stays moist. Even overfilling the water bowl on purpose.
A) they are only active near the surface when the surface soil is moist. Witness these were found after a much needed rain here in SoCal. During hot or dry weather they disappear deep enough to not be found and stay hydrated.
B) there is good science in the journal of herpetology (no better reference than that) that quantitatively showed the moisture level of the substrate that is required to keep the animal from dehydrating.
On another note you may be able to get tiny silkworns in bulk. The more varied the diet the more nutrition he gets of time. I suspect minerals will come from the soil and since you use his native soil then he'll have the minerals he needs. Many lizards will eat soil for minerals.
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AMAZON REPTILE CENTER
