Snakes can easily be placed in pillow cases and then placed in almost any box or container. I only have snakes so I would bag them and then place them in one tub, well the big blood will get it's own tub. Then I have power inverters to run a tstat for uth during the retreat. My bug out safe house is about an hour but being able to run tstats and uth would allow you to really go wherever needed. I know my different snakes require different hotspots but picking a nice middle number should keep them safe until I get out. I would bring stacked tubs(saves space) so I can separate them once safe. I personally would bring a small room heater so you don't have to get lamps or uth for each snake at you're safe spot and again try to find a happy median for them and only run one our two uth for those that require more heat.

Throwing your frozen feeders in a cooler would be good to if you have time and the space to store them where you are going.