I've never done a duck on a rotisserie, but it will most likely come out really good. Moist meat and crispy skin. I would poke a lot of holes allover to allow all of the excess fat to drain out as it turns, this will ensure a crispy skin. Cook until the thickest part of the thigh is 160. Some like their duck medium to medium rare, but I prefer a well cooked bird. With all of the fat a duck carries, it's pretty hard to dry one out. I would baste every so often with cider.