One of my most unpleasant rescues was a pine snake that got up under the dash and significantly burned from the car's heater, so please don't allow free roaming! This snake was burned over 50% of its body and still has shedding issues 3 years later from scarring. This pine snake wasn't a pet, just a hitchhiker, but you get the idea. It was an old car with rust holes all the way through the floorboards and the kid just let the snake hang out in the passenger compartment while he was driving around. He had figured it would eventually go out the way it came in.
I give another vote to a cooler with either hot packs or a heating pad plugged into the ciggy lighter, with the snakes further confined in bags, pillow cases, delicups or rubbermaids. I also feel empty stomachs travel better than full ones. You don't want food rotting in the gut because stress hampers digestion.
The Zombie Mama is here!