What kind of truck (van) do you drive? Does it have bathroom facilities of one sort or another? How long can you hang out in the truck before you must find a toilet outside the truck?
If you have no bathroom facilities in the truck, find a 24 hour grocery store in or near Elk Grove Village. Often, you can park in the street nearby, or the manager may give you permission to park in the lot. It's a suburban area there, free of the crime indicators (barbed wire fences, graffitti, check cashing stores, litter, caged-window liquor stores, etc.).
If you have bathroom facilities in the truck, any suburban office park will do. Those places are quiet as can be at night and street parking is easy to find.
For showers, the easy answer is the TA mentioned above, but it is outside the 25 mile limit. If there are few trucks in the area, that won't matter much. FedEx will find you just the same.
With that in mind, another spot may be the Petro in Racine, WI. From there it is about 50 miles to Elk Grove Village and about 50 miles to Milwaukee. It keeps you outside the 25 mile limits for both express centers but it puts you within a reasonable distance of two respectable freight centers.
In unfamiliar cities, a technique Diane and I use to find a safe place to spend the night is to find a Barnes and Noble store. They seldom locate in bad neighborhoods. They are in busy retail areas where people are used to trucks coming and going all the time. If a 24 hour grocery store or resturant (Denny's is always good) is not to be found, parking on the street near a convenience store may provide everything you need for a given night.