Parking downtown chicago is hell.
Any chance of getting it in a Chicago Suburb? Any place near Rt 290 would be fine, since thats the only freeway and its just a 20-30 min drive to Chicago on it during non-rush hour from the NW Suburbs like Schaumburg or Hoffman Estates or Elk Grove.
Not to mention you wouldn't be subjecting people to paying the horribly overpriced Parking Meters in the downtown area. I am all for free and plentiful parking.
It's the same in downtown LA and San Diego. I got a deal by parking r far away from an event last time I went to LA. $15 lot. Yes, that was a deal.