A sufficiently motivated thief and a golden opportunity will trump anything you do. All you can do is make your property less attractive to said thief than somebody else's.
If you dry camp where there are no other campers within sight as well as multiple means of getting away, somebody could walk away with your stuff. Even kids that just want to play with something they see.
Thieves hate it when there's only one way in/out, that goes past an office. When anything is big enough to not fit in a pocket or under a coat over their arm. When a CG requires a tag hanging on your rear view mirror to be on the premises. If you're towing a TT, and your car is gone.
I remember somebody on the forum that had a heavy chain attached to the TTs bumper and a large dog dish next to it with "Killer" on it in big letters. :)