Preheat oven to 400. Prepare a 12" pizza pan with cooking spray and flour; set aside. In a skillet, heat turkey, barbecue sauce, salt, onions, and bell peppers until vegetables are tender. Roll dough into a 13" circle. Place into prepared pan. Bake for ten minutes. Remove from oven. Spread with sauce mixture. Sprinkle mushrooms and cheese over top. Bake for 15 minutes, or until cheese has melted.