I adapted a sterilite container by taping a heat pad on the bottom on one side. Plug that into a rheostat, then a cigarette lighter power inverter. MAKE SURE you find the appropriate adjustment on the rheostat, then mark the rheostat in case it gets knocked somehow. Use a digital thermometer gun to check your temps. I have also left my snake's 2 hides in, which are plastic dog bowls. In theory, they could hurt your snake if they flew around violently, but I've found with paper towel substrate that even in more intense braking situations, the snake and the hide will just glide forward gently if there is a lot of room. You could even go smaller to prevent that, I just brought my snake's living arrangement... Also, if you stop at night you can put the water bowl back in. And make sure your snake hasn't eaten, but you probably are well versed with this idea. More complex than other successful transports but just in case you wanted another idea 😉