I don't mean to minimize your concerns but maybe I'm asking that you look at the situation from a different perspective. A little burnt out grass is a small price to pay for a good dog who has adjusted his natural instincts to the degree that he has. Rejoice in the fact that he is housebroken and doesn't go in the house. I certainly wouldn't confuse him because he's a few feet off where you want him to be. Certainly it is much more comfortable to stand on the grass while he relieves himself than the gravel. This is a good dog, look at it from his point of view. Maybe put grass in his area.