This is what I do for FedEx shipping. Look at the weather in Memphis- what the temps are going to be in the 10PM-6AM time frame. If it's dropping down to low 80's I feel relatively safe with that, no matter what the daily highs at the origin and destination are.
You drop your snake off at the end of the day- it sits in the air-conditioned building with fresh ice packs till it gets on the truck to go to the FedEx at the airport. Then it sits there, with its still pretty good ice packs till late evening. Then it flies to Memphis, where the temp will have dropped to near the nighttime low, arriving around midnight, where it sits till about 6AM before leaving for the airport in your state. By then, the arrival temps are at the lowest of the day, and if it has to take a truck ride to your FedEx facility, the temps are low and the ice pack is thawed but acting as a heat sink. Then at the destination FedEx, it sits in the AC until you pick it up.
You are way better off buying something like an Okeetee from any of a number of people here on CS.com, that you can talk to, interact with, see the parents of the snake you want to buy, etc. Of all the breeders mentioned above, I've either bought a snake from them or know a _ton_ of people who have, and know a couple of them personally because they live in my state and I've seen their set-ups and stock at shows, or in their homes, and you couldn't go wrong buying a snake from any of them.