I took them from Alaska--->New York In January
For me, it wasn't so much the ride itself but the bitter cold, I'm talking like -40F plus high winds.
Since it was 2 weeks of travel time, I kept them in something that allowed them to get fresh air easily. Originally it was coffee cups but about 1/4 of the way - most froze and I had 4 left. I put them into betta cups and put the cups into one of those small rodent carriers (which was supposed to hold the chinchilla but I neded up leaving her in her 2 story cage for the move). I had it on my lap, under layers of blankets with the heat on full blast for the rest of the trip. And a very unhappy dog on the rest of my lap.
We only did 3 hotel stays in that time and I kept a storage bin with their supplies in the back seat. I only feed them one pellet every other day to cut down on waste production and had a syringe to remove poop from the cups.
How long of a trip and where are you located? Florida won't be so bad as say, minnestoa.