Good News: Magnet came and is pretty damn strong. When I have some time I will begin testing possible locking techniques.
Bad News: My father in law went into my office that had the door closed, saw all my ducting, went into my closet that had the door closed, saw all the holes I had cut for ducting and proceeded to ask my wife what that stuff was for. I am pretty sure he had a good idea, but just wanted to verify his suspicions. I told her to tell him it was for a darkroom, and he was satisfied with that, but I don't think it will be the end of his snooping.
This is why I need to get these locks in place.