Here are my suggestions for the move:

Skip the last meal before packing them up, if it is within 3-4 days. Plan on not feeding them again until you get them back into their permanent enclosures and give them a full week to settle in again.

Put each snake in its own bag. A pillowcase turned inside out will work fine. Tie the bags securely. Then put each in its own small box with a secure lid. If it's plastic, be sure it has holes for ventilation. If necessary, pack some wadded paper around the snake so its bag can't slide around in the box.

Then place the boxes on the floor or seat of your car, but make sure they won't fall or slide around. And make sure they're not directly under an AC vent, nor in direct sunlight.

If you need to spend the night somewhere, take the snakes inside with you, but it won't be necessary to take them out of their packaging.

MOST IMPORTANT....Never ever leave the animals in a parked car during the day!! Even a few minutes can heat that car up to deadly temperatures. When you gas up, leave the windows down and do it as quickly as possible. Plan on eating drive-through during the day.

I've traveled cross-country twice now with my critters, and it really just takes some common-sense planning. Good luck!