In response to the original question, you always run the chance of being bitten. It simply comes with the territory. First of all, being bitten by your BP won't hurt very much. They do not have very big teeth. If you keep snakes long enough, you will get tagged. No reason to be afraid though.

My personal opinion from everything that I have read & learned, is that feeding three large mice every single week might not be the best idea. The reason being if you constantly feed them as much as they will eat, at some point they are almost definately going to go off feed for an extended period of time to sort of catch up & filter out all of that extra food. One small rat or a large mouse or two is just fine.