The link pianotuna gave has a bad placemarker in the Website. The marker is in a cemetery (not pianotuna's fault).
The correct location for the campground is 40.401574ยฐ -95.848110ยฐ
OP, it would also help if we knew what your parameters are - free, hookups, next to highway, etc. "Overnight" to me can be very different than what you are looking for.
2017.5 Lance 1995
2017 F150 EcoBoost, Max Tow
Most camping off-road