If you pack your snakes the way you would pack them to ship in the mail they should all be perfectly fine on a long drive. Maybe a little chilly, but fine. I would avoid feeding them the week before the trip and give them 1-2 weeks when you get to your new home to settle. So: snake bags or deli cups depending on size, styrofoam cooler(s), and crumpled paper to keep everyone cushioned.

By the way...congratulations on getting accepted into your PhD program!