I know the park you are talking about. It's the one where you make that turn by Offerdahl's off of Federal. I understand that airsoft is still cool there and the police are more than aware and cool about it. I know it's a slight bother but what if you converted the opening just inside where you walk in into a staging area and lay tarps or something? I had thought about it a few times since I always worry that some "concerned mommy" type might take one look at us and first thing they do is, you guessed it, grab their phone. If they had their way they'd make us dress like them too.
I was thinking of making a sign to be able to put up blocking the trail going in to warn the public about "airsoft event in progress" and "proper safety equipment" and "eye hazard" just to help cover our asses. But yea, go ring the Sheriff's office and double and triple confirm everything. I'd like to know what you find out.