First of all, thank you for taking up the calling of teaching science. I teach college and grad school science, and I cannot even begin to comprehend how difficult it must be to educate high school kids. You are truly providing the foundation that provides thoughtful, creative and knowledgeable scientists for the future.
I think having a BP in the classroom is a great idea. You have obviously thought out all necessary parameters that must be in place to provide a safe environment for both student and snake.
One last thing that im not sure if others mentioned. You could possibly consider having all students who want to eventually interact with the snake get a permission slip signed by their parents. You can outline on this document, that however unlikely, they are aware there is a chance that the snake could bite them. Its unfortunate, but we live in a litigious society. You don't want a pin prick snake bite to turn into a lawsuit.