Happy Trails!Snakes travel surprisingly well. BTW, when you close the pillow case, another reason that my way is better than tying the end of the bag is that tying it takes away more of the length. You want the snake to have some room to move around inside the bag, not be tightened into a curled up position the whole way. And this way, if the bag should slide over where the heat pack is under the towel, they'll still be able to move away if they want to be cooler. See? You'll do fine- you're asking the right things ahead of time- it's all about prep.
BTW- about that plastic ventilated container that you bought- I use those all the time for my snakes, & I have for years, as temporary containment when I clean, etc.- I do like them, but just not good for travel. Insulation is what you need & they have none.