I'm generally not a vindictive person, however, if I put a lot of effort into something like a solid plant, and some assholes decided it was time to mess with me, I'd definitely try to devise a non-lethal, yet effective way to keep those fuckers out.. Do you have a way to trench around the area and possibly hide the trench? I'm not talking pungy sticks or pits full of treachery, however, a good twisted ankle surprise will not kill anyone and may make them think twice about fucking with you.. Then again, so with a paintball gun filled with frozen paintballs; non-lethal and painful.. A few welts may make them think otherwise, however you'd have to be nearby to really know when they're coming..
Whatever you choose, a lot of these guys make great points and you don't want to attract additional undue attention, especially if growing in your hemisphere is verboten.. There must be some other ideas that folks can throw out.. Hell, even if you could come up with a wireless flood light that is literally blinding, they would think that you're nearby and may run/scatter.. Just make sure to move it every day or every time you go out there, in the event they come back a couple times.. A very bright, motion-sensitive light coming on when dicks are trying to snatch your stuff may make them run without thinking twice about coming back.. Another thing that might work is using deer piss, and hope that coyotes/wolves/predators come nearby.. They won't mess with your crop, and could sway their decision..
Best of luck and hopefully it's not so bad that I hear about it here on the east coast of the U.S.!!!!!