I agree that fences are a dead give away. Same goes for utility flags, string and stakes, etc.
I posted a bunch of no trespassing and no hunting signs around my property. I feel like they still get the message across without revealing too much about my sangin'.
Regarding the deer and turkey, I hear the fishing line works really well as a deterrent but I also learned a new one over this past season I'd like to share:
Tie up some plastic garbage bags and tack them up around your plot. The idea is when the wind blows even a bit, the motion and noise of the thin plastic keeps away critters.
Someone shared that little tid bit with me recently, three weeks later I noticed that just about every veggie garden along the main road
by me has bags strung around the fence, so the idea must be somewhat effective.
Below is a portion of a previous post of mine from a year or so ago regarding security.
Someone on this site recommended a more visually stunning deterrent, a noosed effigy of a sang ripper with a sign on it.
What I did was I towed one of the old vehicles from off a neighbors property to mine, right near my patch, where I proceeded to send roughly 300 shells down range at it out of my AK-47. The peppered paint job leaves a lasting impression.