But I agree that National parks are typically not mismanaged in the ways I described that the vast majority of government land is abused. They are often mismanaged in other ways. See the great Yellowstone Park fire, for an example. Or see the closure of the Grand Canyon over Federal budget battles.
But I'll make you a deal - sell off all the Federal government land other than the parks with the stipulation that the land can only be purchased by real human beings (not corporations) and only by American citizens. But don't sell the National Parks and instead turn them over to the States. I would be okay with that compromise.