One of the IL SPs we liked the best (and we preferred WI SPs - better facilities in general). You won't find it heavily wooded, but there should be some good shade in some sites. Not many sites are ideal for a rig of your size, but a few may work well. If you can get reservations, do; otherwise you may be trying to sandwich yourselves into whatever sites are left over. We were there last in 2008, in site #105, a pullthru with plenty of room for our 34' TT & truck (see sig pic). Unfortunately I didn't write down the other sites which we would have fit in.
2020 Toyota Tundra CrewMax 5.7L V8 w/ tow pkg, Equal-i-zer
2020 Lance 2375