For Kiley Miller and John Rzeczycki, owners of 160 acres of wild desert outside Moab, Utah, Easter brings jeeps. Hummers, too, and modified pickups, and stripped-down rock crawlers—by the tens of thousands they descend on Moab for the annual Easter Jeep Safari, one of the nation's largest off-road-vehicle events. The jeeps whine through gears on a windswept uplift named Black Ridge near the couple's property, leaving a spoor of beer cans and brake fluid. Once, a group of jeepers left a message on one of the Private Property signs Miller and Rzeczyckihad put up—a noose, as carefully knotted as a...