More than 30 years ago, Mary and Peter Gustafson bought a 200-year-old log cabin in the village of Lucketts, a community in Loudoun County, Va., minutes from the Potomac River and the Maryland border. While development is spreading to the hamlet, Mary Gustafson said, much of the unincorporated village has remained unchanged over the decades. There’s one traffic light, and then rolling hills, pastures and farms, horses and cows, and views of Sugarloaf Mountain.