Being in FL, you may be able to get away with heating from above, I'm not sure, but i know for a fact it would be near impossible to maintain proper temps and humidity in that tank in MA.

I would look into a RHP if you're definitely using that enclosure, but I still think that 12" is way too small a floor space for an adult BP.

I'm not trying to rain on your parade, just trying to help you and your snake.