Preheat oven to 350 F.
In small bowl, combine brown sugar and jerk seasoning. Rub mixture all over outside of chicken. Cut one lime into quarters; insert into chicken cavity. Add cilantro sprigs to chicken cavity. Place chicken in roasting pan and surround with pineapple chunks. Place in oven and roast for 45 minutes.
While chicken is roasting, juice two remaining limes. Remove chicken from oven; add sweet potatoes, rum, chicken stock and lime juice to pan. Return to oven and roast for another 45 minutes to one hour, or until internal temperature in thickest part of the thigh reaches 180 F.
Remove chicken from oven and place on sheet pan. Tent with foil to keep warm. Remove pineapple and sweet potatoes from pan and reserve. Pour sauce in pan into serving dish; add chopped cilantro.
To serve, carve chicken or place whole chicken on platter. Surround with sweet potato/ pineapple mixture and pass with sauce.