Dry ice would work great. I am told but need to confirm that a certain amount of dry ice is OK. By the way I packed 100 ponds of frozen halibut in two seperate suitcases and it made it from Elfin Cove Alaska (80 miles west of Juneau) via float plane to Juneau to PHX without thawing. Wrapped in newspapers 9 hours total. Any info re dry ice being permitted? You all are awesome what a great resource.