How about lagging throu the back of it into the wall? There would be a little drywall cleanup when you move, but it would be enough to secure it from the basic thief. If somebody comes for your stuff and truly wants it, they’ll get it no matter what you do. It’s like locking your car. That keeps 99% of the chickenshits out, but that guy who wanted your stereo is gonna break a window. 2 lag bolts, or even 1 really will slow a pair of guys down. Run in from the inside it would have to be open to get at it.