Now let's answer your questions. Racks are more escape proof than enclosures when they're shut all the way. Animal Plastic sells display enclosures, and all of them come with stacking pins. They are little pins that allow you to stack enclosure in enclosure without them sliding or moving out of place. Would you need different thermostats for snakes with different heat requirements? Yes. A corn and Ball could share one at 88-90°. Idk what the heat requirements for your other snakes are so I couldn't tell ya. I'd go AP display enclosures. They'll be nice and neat, but you'll actually see your animals when you want to.