I copied Lea's Thomas-built modification to the Kirbystud garage door deadbolt lock on the back door. My back door had some internal metal that prevented me from mounting the lock as high as it really needed to be, but it works okay. It definitely stops the door's bolt from traveling, but repeated slamming of the handle might overwhelm it. Of course, anyone who wanted in that badly would probably just smash the lower window out. Maybe I should put expanded metal over the lower window...or all the windows...maybe I should have bought a prison bus!
It looks formidable from the outside, what with the padlock and the deadbolt cylinder in view.
...except for all that glass!
The whole fitting procedure is here http://www.skoolie.net/gallery2/Kirb...ltModification