The best solution is to close the parks at the borders.   Build big parking lots at the entrances.  Charge for parking.  Have horse and bicycle rental businesses at the entrances. Allow no other form of transportation in the park except hiking.   Shut down all the cell phone towers within the park.  Make it clear that rescue will not be provided, and body recovery will be by volunteers and will at best be spotty.  This will be environmentalists' dream realized.   I am ok with this plan as I've seen Rocky Mountain National Park turned into a world class zoo, with hundreds of gawkers on the summit of Longs Peak on any summer day.   Let's get mountaineering back to the challenge that it once was.  The $70 fee is financing buses and flush potties for altitude sick flat lander tourists.