Hey Rocky, I've got quite a bit of experience hunting in that part of the state, since I went to college at Southern Illinois University. I've hunted both public and private ground down there, and can tell you this. The shawnee national forest is big and harbors some big deer. There are so many places out there where you will never run into another hunter that I normally found less pressure on it than the surrounding private areas. If you are looking for a big buck, try to stay within the counties that have better soils down there. That part of the state is much different than the famed "golden triangle" are of western Illinois. Go to counties that have corn an bean fields. These areas have better soils and grow bigger bucks.
Here is a good one for you. The last time I hunted down there, I was chasing a big buck. During the late season I saw him 3 times in 3 days. I ended up moving my stand. On the fourth day he walked within 20 yards of me, but he had shed his right antler! I had to pass. I looked for along time for that shed but never found it. oh well.