I'm not sure where you are, which is to say: is it cold now or is it of a "reasonable" temperature? If it's cold, my advice might be a good starter but will need additional modifications from others. If it's reasonable, you should be fine. Overall it won't be a big deal because it is a short drive.

I drove 2,400 miles and six days. Be thankful your adventure won't be like that. My approach, with advice from many was:

1) Get a plastic bin with a locking top for each snake (I'm assuming you have 1 from here on), drill holes in the top and maybe the sides
2) Get two pillow cases that are each big enough to hold the BP
3) You'll put the BP in one of the cases, bundle the open end together, and fold it a few inches 180 degrees
4) Tie off the first pillow case with something like rope or string or maybe electrical tape
5) Put the first pillow case inside of the second one, and close it off the same way
6) Put the dual-pillowcase package into the bin and put the lid on

I strongly suggest having a digital thermometer that you can continuously monitor. DO NOT put the bin on the floor, people have had their animals KILLED doing this: It gets hotter than you think.

Have a white towel big enough to cover the entire bin. This way you can adjust how much it's covered from the sun, if needed.

That's the basics, you'll get other ideas from others regarding cold temps.