I agree with AJ52. Find remote locations that can't be easily accessed by road or trail. I'm in your same boat in that I only have access to public land. I've been spending the last few weekends in a state forest not only looking for deer sign, but trying to figure out a spot that's just inconvenient enough to deter the average idiot, but not so out of the way as to make dragging out a deer impossible. The spot I've settled on is on the shore of a partially drained reservoir and to get to it I have to walk several hundred yards across a power dam, and then scale the cliff like rocks that used to be submerged. I found quite a bit of deer sign there as well. I figure it's a hard enough hike to weed out your average hungover dolt.