Make the Turkey Brine: Combine 2 gallons water, 2 tablespoons whole peppercorns, 1 cup brown sugar, 1 1/3 cups kosher salt, 2 sprigs sage, 4 bay leaves, 7 sprigs rosemary, 2 halved heads of garlic, 2 quartered apples and peels from 2 oranges in a large stock pan. Heat the brine until sugar and salt have dissolved, stir occasionally. Remove the brine from the heat and bring to room temperature. Place the turkey in a 32-quart plastic container. Pour the brine over the turkey. Place the turkey in the fridge and let brine for at least 12 hours, up to 24 hours.
Remove the turkey from the brine. Pat dry and set aside.
Prepare the grill for indirect cooking at 250-275 F. Add your preferred smoking wood to the fire while the grill is heating.
Tie the sage, bay leaves and rosemary with kitchen twine.
Stuff the turkey with the peppercorns, herb bundle, garlic and onion.
Lightly coat the turkey with the olive oil.