You dont have to build a big rack. You could build just a one slot rack out of PVC. Basically it would a roof, bottom, 2 sides and back and keep the front open so that you can slide your tub in and out that way it wouldn't take really anymore room then the tub itself but still hold heat in. You would want to make it so your snake couldn't get out between the roof and the tub so you would only need a tiny gap and have it so there's a little clearance on the sides. If your going to use the lid on the tub you could just make it so the roof clear the lid of the tub a little.

Sent from my SAMSUNG-SM-G890A using Tapatalk