Same here: scenery is nice, neatly taped on, or just dark plain paper/cardboard...& since you live in a colder climate, you can insulate behind the paper with
various easily-obtained materials to keep warmth in the cage where your BP needs it. As AbsoluteApril said, black poster board (it has a foam core) or some
ppl use styro-foam sheets cut to fit, even corrugated cardboard or a roll of cork sheeting will work. The white walls behind this enclosure reflect more light
than most snakes appreciate, so covering the back, sides & most of the bottom* will take care of that too. (*if using UTH, remember it does need to be vented)