Well, you are correct, virtually nothing on the internet. I looked at Google Maps and there is a S Campground Road in Raccoon Lake Park, but no evidence of a campground, There is nothing on the City Parks and Recreation web site about it at all and on
https://seecentralia.com/raccoon-lake/ which I think is a city owned web site, it does not mention camping. Possibly the campground road is named after a old (1800's church campground).
Jumping over to Carlyle and Carlyle Lake, there is clearly a campground on the east end of the dam (McNair Campground), with paved sites and you can even see the shadows of the power pedestals on each site, yet the city parks and rec web site does not mention camping at all, HOWEVER, Carlyle Lake is Army Corp of Engineer owned, and on a COE CD-ROM I have of all Corp owned lake recreation areas, it shows campground, water hook ups, electricity, showers, etc. Another campground shows adjacent to the spillway, in the Spillway Recreation Area.
Recreation dot Gov shows a campground with 109 sites on the west side just north of the marina,
https://www.recreation.gov/camping/campgrounds/233483Spillway east side has 15 sites.
https://www.recreation.gov/camping/campgrounds/233478The McNair Campground has 32 sites.
https://www.recreation.gov/camping/campgrounds/233478Campendium has this to say about campgrounds on Carlyle Lake
https://www.campendium.com/illinois/carlyleIt is 11 to 15 miles from the campgrounds in Carlyle to Kaskaskia College (US 50 east to State 5 south at Shattuc.)
Hope this helps.
Charles
'03 Ram 2500 CTD, 5.9HO six speed, PacBrake Exh Brake, std cab, long bed, Leer top and 2008 Bigfoot 25B21RB.. previously (both gone) 2008 Thor/Dutchman Freedom Spirit 180 & 2007 Winnebago View 23H Motorhome.