Clean it up, stack the trash at the entrance to block the way, and park your butt by the trash. Extract $5.00 from every shooter that attempts to use the range in payment for your making it suitable for continued use. Tell the State, when they most assuredly will come to remove you from your good works and money making idea, that they can take your place and earn the "Use Fee" if they keep the place clean. Tell the State that they are getting your man-hours for free. Otherwise, it is $75.00 per hour to haul trash and debris and they owe you for 3 days back wages. I bet the local Judge would see it your way. When someone shows up to shoot and attempts to haul in tires and their other trash, show them the exit. There will be others that will see your good works and applaud your actions. It could also be brought up as a Boy Scout Service Project.