The Elkhart County Fairgrounds (Indiana) offers camping. There's a fee, but for an over night, it's a Lot nicer than a Wall Mart. And you might get lucky and see some folks running their horses on the track.
Click here for more info. We've stayed at the Fair Grounds several times.
This was our campsite in October, 2013. We did RV factory tours that week and spent time in Middlebury, Indiana.
This was in 2007. Now this was a fun trip: