I'm planning on getting a dumerils boa in October at the reptile expo and I was wondering if a flexwatt, regulated obviously, only on one side of the vivarium will heat the entire thing or if I'll need another heat source to keep the rest warm. Room temperature will be about 55-60 in winter and 70-76 in summer. I've never used a flexwatt before, only radiant sources(heat lamps and ches), but now I need to stack the cages so I can't use that for the cages with others on top of them, obviously.