I originally had all boas take a good long drink days prior to being cooled. They are currently in small rubbermaids with holes drilled in the plastic. Each rubbermaid is inside a large wood-framed, styrofoam-lined box so that I can maintain temps. Ventilation is minimal since air-current is virtually non-existent. Also, relative humidity shouldn't be too low as the temperature-controlled box is in the cellar. Since they just drank prior to brumation, perhaps I will place a small water dish in with each boa for 24 hours or so some time at the beginning of Jan and Feb. This seems like it might work. I do not wish to leave a permanent water source in there, given the setup, and I would prefer to disturb them as little as possible during this time.
Cheers.