Checking to make sure I have my facts straight.

[Foschi Exotic Serpents]

Sounds right to me. You should publish a book Danouet I mean lol! The OP is not far off tho.

As far as the heat goes. Your boas will let you know if the hot side is too hot. They wont sit there like a BP will and burn them selves if its too hot. If they never go to the hot side, even after a meal, take it as a sign and bump it down a degree or 2 until you find the perfect temp for them.

Remember, boas were one of the only snakes in the Barkers outdoor enclosure study that actually moved from the cold to the warm area of the cages to survive. The other snakes showed no ability to seek shelter from the cold and allowed them selves to freeze to death. If this holds true for cold, then of course its true for heat as well.