If you're there two nights, your best bet is to hire a driver/guide to take you straight to the portion of the Wall that's closest to the airport. I can't remember which one that is, but it's not hard to look it up. Then, from the wall, go back to your hotel check in, relax, and go to dinner. For duck, every time I've had it has been with a group, and I'm not sure there are smaller portions. It's usually done in a variety of ways, so it's a lot of food.