Soak 1 pound of wood chunks in water 30 minutes to 1 hour.
Bring vinegar, 1/4 cup ground red pepper, 3 oranges, and 3 lemons to a boil in a Dutch oven over medium heat; cook 10 minutes. Remove vinegar mixture from heat, and cool.
Combine remaining 1/4 cup ground red pepper, brown sugar, and next 3 ingredients. Rub evenly over pork. Drizzle 1 cup vinegar mixture over pork; set aside 2 cups vinegar mixture for basting, and reserve remaining mixture to fill the water pan.
Prepare charcoal fire in smoker; let burn 15 to 20 minutes.
Drain wood chunks, and place on coals. Place water pan in smoker; add vinegar mixture and remaining 2 oranges and 2 lemons to depth of fill line. Place pork on lower food rack; cover with smoker lid.
Cook pork roast 6 to 7 hours or until a meat thermometer inserted into the thickest part of roast registers 170°. Baste with reserved 2 cups vinegar mixture every hour after pork roast has cooked 3 hours. Add more charcoal, remaining 1 pound wood chunks, and vinegar mixture to smoker as needed.