If you have a good red ant bed you can place the skull on it and let the ants feed off of it along with the maggots.
My problem where I live the ants would take a very long time to consume that much material and a coyote or racoon would be likely to dig it up even if I were to place a cinder block on top of the lid on the hole.
If you don't like the pure white that most skulls are now done it you can just cook it and then leave it natural without putting any bleaching chemicals onto it. Over time it will turn yellowish from the natural oils that are left in the skull.
Myself I actually like the whiter skulls as compared to the darker ones and I have both.