May I put a point up? I know the big question is why we can't put caches on National Parks. I don't see why we can't but right now we have to follow their rules. One way to help get it across to them (NP) that this is not a bad thing is to start at the local level. (ex. city/state)
If we can show them that the local people are letting us do it then maybe they will take a more serious look into the matter.
I know this from my experience from working at the state parks here in MS. I have showed it does the park good to have a geocach on it. I have also showed that geocachers do not mees up the surrounding area like non cachers. I have also showed that cachers don't litter like regular guset do. So in doing that it has been a positive reaction in getting other caches placed in the local and private areas.
So just ask and inform people of what is going on and what it is about will help out more than anything else. If you get a NO then maybe relook at how you explaned youreself or just move on to a different location and ask there.
Wall Doxey State Park, MS