Bob.....Go to a truck store and buy some good, heavy rubber mud flaps. You can buy ones for the front of a semi that should be just the right width. Mount them against the back of the wheel well and make them so they are about 1.5" off of the ground. Since there is no overhang issue, the flaps won't change height as you go up or down inclines causing the flaps to drag and kick up rocks. Keeping them low will keep the rocks from getting under them.