ST. LOUIS (KTRS)  Gander Mountain is coming to O’Fallon, Missouri – that’s according to investor and Camping World CEO Marcus Lemonis. On his Twitter feed, Lemonis confirmed an O’Fallon, Missouri, Gander Mountain is planned and that the Gander Mountain stores in Chesterfield, Fenton and O’Fallon, Illinois will stay open. Camping World bought Gander Mountain this year out of bankruptcy.