If I had to leave anything behind (and it would seriously pain me to have to do so), I'd leave a note on waterproof paper pinned right to the outside of my pack/stuff with instructions to any passers by that if it were beyond xx/yy/zzzz date and I had not returned, to take my stuff to the nearest ranger/conservation station and report it.

That move could save my butt if something had happened to me while I was doing whatever it was that made me leave my stuff behind.