I've stayed at the Hollywood Casino campground in Joliet Illinois. Here is a blurb from their website:
"Hollywood Casino Joliet is the only casino in northern Illinois to offer an on-site RV Resort. Open seasonally, our RV park has all the conveniences of home, including water hookup, 30 and 50 amp electrical hookup, hot breakfast, laundry facility, wireless internet, business center, private rest rooms and showers, dump and beautiful landscaping."
This is the only decent campground near Chicago of which I know.
