I've hunted Fulton and Mcdonough counties in the west central part of IL four times now. Good hunting and always see big bucks. Choked a chip shot on a 150 class buck a couple years ago and still haven't quit whining about that one.
Finding decent public ground is gonna be tough. Suggest paying an outfitter and going that route. You can get a good 5-6 day bow hunt for $1500 or so, semi guided including meals and lodging.