Last fall, I paid a butcher to cut/wrap/freeze my Mule Deer (SE Montana), I then bought a GOOD cooler, loaded the meat in and found some dry ice. The third day, the meat was still frozen hard/solid (in Seattle).
I am planning on a different approach for the future. Setting up my rig for dual batteries, a solar charger, and a 12V fridge/freezer. Butcher/wrap/freeze it myself and transfer into cooler with dry ice as overflow when the freezer is full.
When I was hunting in Alaska, and transporting my meat home, I'd cut/wrap/freeze myself, and take the boxes of frozen packages to AK Air Cargo and request them to keep it frozen. I had ONE instance when it was left out in Kotzebue, and began thawing. However, in spite of the incompetence of the Kotzebue ground crew, my meat arrived to Seattle in good shape and not spoiled. AK Air Cargo simply had to deal with some blood seepage from a couple of packages. When they tried to whine to me about it, I set them straight with what happened, their whining stopped abruptly when they realized I might file a complaint against their Kotzebue ground crew's incompetence.
If the meat is fitting the category of potential "Chronic Wasting Disease", you MUST NOT attempt to bring skull/spinal chord (fresh/raw kill) across State lines. My deer skull/antlers are being professionally mounted and are then OK to bring across after I go get it from my Montana taxidermist.