Hi, you could maybe look at how they are shipped and try that as well for moving?
We got an axie from Germany once that took about a day to get here. He was in a plastic bag half filled with water and the other half air. That bag was in another bag and finally a styropor box. You can put an ice pack in the box to keep the temperature from going to high.
Maybe others that have experience with moving axolotls can help better , good luck!