1. Cut top 2 inches off sourdough loaf, reserving top; hollow out loaf, leaving a 1-inch-thick shell. (Reserve center of bread loaf for other uses, if desired.)
2. Drizzle 2 Tbsp. vinaigrette evenly in bottom bread shell; layer with half each of turkey, cheese, and peppers. Repeat layers with remaining turkey, cheese, and peppers, and top with bacon. Drizzle evenly with remaining 2 Tbsp. vinaigrette, and cover with reserved bread top; press down firmly.
3. Wrap in plastic wrap, and chill at least 1 hour or up to 8 hours before serving. Cut into 4 wedges.