Until the thermostat arrives you can regulate the UTH using a lamp dimmer. Stores like Lowes and Home Depot sell them for about $15.

Covering the top of the tank with foil or Glad Press n Seal helps keep in humidity. You can also make a humid hide for him out of a large zip-lock food storage container, just cut a corner off of the lid so he can get in to it and add some damp spaghnum moss or pure cypress mulch.