I use the rubbermaid tubs (74qt I think) for my ATB and they do hold heat and humidity pretty good.
ATB....now THAT's a handleable snake...J/K.
You could use whatever substrate you want in the tubs. Back when I used to breed, I used aspen shavings, cypress mulch, paper towels, and even newsprint depending on the species. Just watch while it eats on the shavings that it doesn't ingest some while it eats. The fibers are sharp. Also, never use cedar shavings. For ease of cleaning, i'd use the carpet, paper towels or newsprint.