We went to visit family, and parked in the Cook County Forest Preserve's Camp Sullivan. Camp Sullivan - Forest Preserves of Cook County
Keep in mind their mission is to teach city folks how to camp, and RVs are not their main focus. You'll see a lot of kids in pup tents and cabins. But they do have 10 tent sites set up with electricity, which are reserve-able. The surprise is that these brand new sites are wired for 50-30-20 Amp service! No water or sewer, I guess these are more designed for pop ups. The host filled our fresh water tank from a hose at the bathroom. Our site was right across the road from it, and it has an outdoor dish washing sink, so we did all our daytime needs there, and only used the camper during evening. Our tanks did fine for the four days we were there, and we dumped them at the next site.
As you can see by the pic, the site is small, and expensive ($60/night on weekend for non-residents of the county). But it served our needs to visit family, was clean, nice, and friendly. The staff are there 24 hrs.
Left to right, its me, my sis, my wife, and bro-in-law.