This may sound strange but ants will clean a skull pretty fast. If you have fire ants in your territory, lay the skull next to an ant mound and the ants will clean it up quick, getting into those tiny crevices. Watch that nothing carries the skull off in the process.
Actually, this is a very bad idea if it is something you care about. Teeth will be lost as well as the whole skull if something runs off with it or chews on it as you noted. In addition, the mineral staining from the ground and ant debris will many times be permanent leaving dark brown or yellow stains.