A simple solution would be to keep a portion of cached stocks available and easy to find by a thief...the trick would be to 'bait' to surface of
cans/bottles/fuel container handles with a skin absorbed contact poison of some variety.
Maybe a large wedge of dried toxic funghi in a jar with a good splash of pure alcohol and left to 'tincture' and then the resulting solution applied
to the surfaces of stealable goodies that will only affect handling with bare hands
By the time the effects begin the theives may put the effects down to plundering tainted supplies at the least, or have a very very very bad time at
the best