Lauren wrote:
There are no rv parks in the near suburbs of the Big Windy. I would suggest you do take transit of some sort in though.
That's not accurate. Two parks within the Forest Preserves of Cook County system have RV campgrounds. You can find more information here
http://fpdcc.com/camping/. This are in the city limits of Chicago. You can get an Uber from the campground to the nearest train station and be downtown in no time.
If you can boondock then you can also make a parking reservation at the McCormick Center Marshalling Yard which permits overnight parking. In good weather you can wall to the Red Line station near Chinatown or again take an Uber to the train station.