I have camped in the area but not at the state park. My DW likes full hook ups and most IL state parks do not offer full hook ups.
We have camped in Utica IL, at both the KOA and at Hickory Hollow camp grounds, both of these camp grounds have full hook-ups. The KOA has narrow sites but typical for KOA. The Hickory Hollow camp is near RT 80 and you might hear truck noise all night depending on were your site is.
We usually camp at one of these two camp grounds in late April or early May for our first camp out of the camping season. This is to make sure everything works after winter storage of the camper and we our close to home if we have an issue.
I would go on line to this site and read the reviews for the state park and other camp grounds in IL.
http://www.campgroundreviews.com/
Jim