Parking a Motorhome in Chicago?? Suggestions..

Some friends are going to visit us when they arrive from CA in their motorhome. They cannot park on the street near us so we are looking for some place they can park their motorhome at and stay in it while visiting the Chicago area.

Someone told us about a spot near the Lake by McCormick Place but I cannot find any information about it. Anybody know about this place, name, phone number or any other information?

The closest place I have been able to find is the IL State Beach campground but that is about an hour North of Chicago in Zion, IL.

We live on the North Side of Chicago.

Would appreciate any and all suggestions or tips from folks.

TIA, John S.