Not trying to be negative but more realistic. For the area I live that would all just be a waste of time. Go idea though and the signs look good but here everyone on the road frontage would have a bullitt hole in a short time. Mostly likely the people that would not trespass wouldn't anyways and the ones that will realy are not going to care if there is a posted sign in a tree or not.
A person can spend 200 bucks on store bought signs or spend their weekend making them, but if no one can be there to inforce, your gonna get locals that are gonna see when your there n not and be like well he's only down on weekends n they'll do what they want mon- fri lol