We are taking a small chest freezer this year and plan on plugging it in at the house. We've done it in the past and it works great. We have a 16 hr drive home and everything is nice and frozen when we get home.
I was in a Cody 2weeks ago and one of the shops on the Main Street had a bighorn ram skull for sale. I think it was around $1500-$2000 if I remember right.