There is the fairgrounds in Springfield. It's 5 miles from I-72. The fairgrounds can be full other than during the state fair. There are horse shows and other events all thru out the year and many of those fill the campgrounds. Some of the fairgrounds campgrounds is on grass with some shade and some of it is in the asphalt paved parking lot with no shade. Quite a few of those in the parking lot take quite a bit of blocking to get level.
There's also Carpenter Park a city campground north of the fairgrounds in Springfield. It's 5 miles from I-72. It's grass with limited shade.
With both the fairgrounds and Carpenter's Park they're close to the city sewer plant. Most of the time there's no smell but if the winds are coming out of the right (wrong) direction then you do get some odor.
Double J south of Springfield is the quickest and easiest to get in and out if just passing thru.
