Well, the other female BPs will not be a problem. I've done the same thing, and had the smaller females not stop eating thru-out the season.
Its the Boa I would be concerned about, and I have no real knowledge as to the husbandry of Boas (yet). I would do some research and see what you can find and if it doesn't work, get another thermostat to just control the Boa.
Good luck!