I think you should post heavily if you can. It keeps the honest people honest and the others, well, there's not much you can do other than talk to them if you have the chance and call the conservation officer, which in a majority of cases won't help if you don't know who they are. You could also post signs near prime spots warning that trail cams are active and trespassers will be prosecuted, even if you don't have any trail cams. Other than that, it's working with the neighbors to watch out for one another's land.

Good luck!