RE: Dry Ice
If you can freeze the head solidbefore your trip home that is great, place it in a large plastic trash bag, you can also double the bags, place it in a cooler. Or bag it and place it in a cooler on top of ice, with ice on top of it. Don't allow water to get on the hide, if placed in a cooler pull the drain plug. I took two bucks in ILLINOIS last year, my drive home was 18 hours as well, I had time to fully freeze the heads solid, they where fine when I got to my taxidermist shop