This was brought to my attention by a friend in Dubuque. I checked it out on the website, and rang the customer service department of the company, who confirmed what I was told.
The sports and outdoor outfitter chain Cabela's welcome Rv's at some of their stores, have campgrounds (min fee) attached to others. Some have restaurants and other facilities for those who wish to spend the night. From all accounts it sounds like another secure place to sleep in the car, for those who are so inclined.
For further information check out Cabela's home page, click on retail stores, click on a store's location on the map, click on store hours and amenities and there you have all the details. Any store which facilitates RV Parking also allows cars to park there.
I plan to check this out in the next week or two, when I will be in an area where there are some of these stores.