How do I keep ice cream frozen with dry ice for a 2-hour car ride WITHOUT the ice cream getting rock hard?

I made homemade ice cream to take for Thanksgiving, knowing that I have access to free dry ice in pellet form through my job.

During Sandy when we had no power for a week, I had two large mixing bowls in the bottom of my refrigerator filled with dry ice. I noticed that some things on the shelf directly above it froze, despite being several inches above the dry ice.

That being said, is there anything I can do during this car trip to keep my ice cream from getting rock solid? It’s the perfect, fluffy consistency right now, and I don’t want to ruin it :)