I live in Old Orchard, but have a camp between Bangor and Machias... If you have the time, take a ride down Route 9 towards Calais (The Airline). Just let your mind wander and you'll find plenty to hunt. Also, you could try the banks of the Machias River or head down to Machiasport during low tide if you're into relics. If you get as far as Jonesport, don't turn around in Martha Stewart's driveway because she'll call the cops... :-) If you want to try finding any of the old logger's camps or hunting camps, my only piece of advice is: bring a GPS.
As far as the state parks go, I've never had a problem getting a permit, just ask the ranger. I've gotten a seasonal permit as well for some parks.