They don't need much. I have a run about as big as your run with your hen house on it, but the walls are six feet and it has a chicken wire top. Part of it is tarped. There are some areas where they nest, but not in boxes, just cubbied areas with straw. Also a few wading pools. You'll be changing them daily. I have 2 pools for 6 ducks. They enjoy it when it rains. Under the tarped area is where I keep their feed so it doesn't get wet. I had all these plans for greens growing for them, and started wheat grass in large patches before I put the ducks in. It was gone in 2 days. Don't bother. Ducks are a blast, fun to watch. And taste good, too. Just butchered one yesterday...I promised one to a neighbor and boy was she happy. She had her daughter bring over a chicken for it. A live hen, in my kitchen. I told her that it was ok, just a gift, I really don't need a chicken. But she insisted.