If you like to take walks in the woods or hike check out Turkey Run SP in Indiana. There are several trails and they are all rated on their website.
Carlyle Lake (IL)is nice, the State Park is open all year.Some COE will be open.
Garden of the Gods (IL), Pharaoh campground, dry camping in the tall pines. There are other nice state parks in So. IL. There is a wine trail in southern IL.
Maybe head over to the Blue Ridge Parkway, Asheville, Smoky Mountains for spring flowers. If you like to ride bikes check out the Virginia Creeper Trail near Damascus, VA it is slight down hill grade. The bike shop hauls you to the top or 1/2 way. Beautiful easy ride down through woods, bridges, streams. There is a small RV park in town, Laurel Creek RV Park about 12 FHU sites. Roan Mountain SP in TN is a very nice park but not really near anything.
We visited the Jack Daniels Distillery tour (TN) in the past. Nice tour. Campground nearby.
Enjoy your trip and new rig!
Marcia