Dirt as substrate.

[guidofatherof5]

I never see my snake drink water, although I'm sure he must, but never does he go in the water bowl to soak. Thought garters liked to go in and under water at times.

They do, you're just not seeing it. Some like to soak and other don't unless they are ready to shed.

[Albert Clark]

Bio active enclosures seems to be what you are describing and there are several types that are commercially available for your consideration. I will try and get the link posted for you.