We've gone a slightly different route on head mounts.
We (wife, father-in-law and I) place the skull in a bucket of water for a few weeks (antlers out of the water of course)
Still a bit of a mess to clean out the vicera (eyes, skin, etc) but its fairly quick and efficient at cleaning off the skull.
Merry Christmas!
Might try that next time, as long as there are no squirrels on the bucket.