I think your best bet would be to use stearlite sweater boxes for them , and I agree with the paper towles over dirt ( its just like putting them into quarenteen ). People travle to show all the time with frogs for sale, and sometimes spend 5 maby even 6 days travleing with them. I myself have picked up frogs at shows and had plans to stay a few extra days after purchaseing them. I allways brought an extra plug in heater ( for when we were in a hotel room ) in the winter and picked up multiple 12 hour hand warmers like the kind you can find at menards. these can be taped to the side of a sweaterbox to provide a bit of direct heat if it was really that cold.