Some suggestions:

Set up the traveling container as you would for the day of travel, hot water bottle and all...and put a thermometer in there to find out just how warm it gets when its all closed up for a period of time. (And make sure there's some sort of ventilation...I'm not sure how airtight those styrofoam containers are.)

Be sure to put the snake in a bag. An inside-out pillowcase will work fine...and tie it very securely closed. This will help prevent any possible escapes, as well as help the snake feel much more snug and secure.

If you think you may buy another snake, you should definitely set up a second, separate carrier. You could put two snakes in one if they both came from the same source...but you don't want to risk the health of your current snake by exposing it so closely with a new snake that may be carrying mites or some disease you can't know about.