Brush the bread shells with some of the reserved marinade. Sprinkle fontina cheese over shells. Divide artichoke hearts, Canadian-style bacon, tomatoes, feta cheese, green onion, and oregano among shells.
Transfer the bread shells to a large piece of double-thickness foil. In a grill with a cover place foil with bread shells on the rack directly over medium heat. Cover and grill about 8 minutes or until cheese is melted and pizza is heated through.