Wilson Island State Park is part of the DeSoto National Wildlife Refuge
It is true that the campground is a big open space with little tree cover, but it is part of the DeSoto National Wildlife Refuge, and there is a ton of trees, trails, and wildlife around the refuge.
It is right next to the Missouri River, and although the park and campground are in Iowa, the DeSoto National Wildlife Preserve is in both Iowa and Nebraska.
You have to pay separate fees to enter the Wildlife Preserve but it is worth it. The entire area is beautiful and has great views of the Missouri River. There is a visitor center and a few other attractions but the trails and the Missouri River are the best feature.