It seems no amount of security will deter the determined thief.
My friends in the Wyoming USA point out that a semi automatic shotgun usually works as a deterent. They lock nothing, truck is left with keys in the ignition. But in Wyoming if a person comes onto your property intending to comitt a crime you are entitled to use "reasonable force" to protect your property. The definition of "reasonable force" includes shooting someone dead.
A different world and not one I'd care to live in.