You might try making your future hides puzzle caches. I imagine that whoever is taking your caches is too lazy to try to figure out the real coordinates. Jaygill started doing that a while back because he kept having his ammo cans stolen. He would have to comment, but I think it has worked OK for him.
"Wildness is a necessity." -- John Muir
"When you go to hide a geocache, think of the reason you are bringing people to that spot. If the only reason is for the geocache, then find a better spot." – briansnat