If the GPS has an ONX chip it can be wrong and will not stand up in court. I personally know of lands demarked wrong on the ONx maps because our county GIS has it listed differently than it should.
For answers to questions on access for the walk in areas talk with your local GW. Most of our GWs are great folks and would rather help you be legal than write you up.
Also take the time to go to a season setting meeting in your area if you haven't missed them. Great time to talk with G&F folks about hunting areas near you.
