Paul Wolff campground, Kane County Forest Preserve. Very nice, clean, well maintained park.Water and elec. hookups, 2 dumpstations onsite. 5 minutes south of I-90, 30 or so miles west of Chicago. Campground is on Big Timber Rd., Metra train station to the city 5 minutes east on Big Timber, easy commute downtown. Only downside is they don't take reservations but a visit originating on a weekday will usually guarantee you a site.
You can check out reviews on rvparkreviews.com, park gets excellent reviews from others that have done what you are looking to do. Water IS very iron rich though, so would recommend a filter.