The Wall Street Journal reports: An Exhilarating (If Risky) Family Adventure in Bolivia The remote Salar de Uyuni salt flat is an unlikely, unnerving—and unforgettable—vacation spot By Hilary McGregor WE WERE HURTLING toward the edge of Bolivia’s Salar de Uyuni salt flat in a Toyota Land Cruiser as the sun was sinking, turning the world…