My wife and I camped there in December. It was nice and quiet! A leaking tire kept us from making it down to the southern unit, but we ran around the northern part near Bloomington some.
There are a bunch of dispersed sites along (IIRC) county roads 1500, 1460, and 925. Just south of Lake Monroe, find where Tower Ridge Rd intersects with IN446. From there, head west on Tower Ridge. Just past the tower, turn south on 1500. You can loop back to the tower via 1500, 1460, 925, and Tower Ridge. We returned home heading northeast from there. That area turned out to be more private land than public. I'm sure we missed lots of good areas, though, since we were only there for one full day and wasted much of that on the tire issue.
I pulled the above road numbers from Google maps. We used a DeLorme Gazetteer when we were there. For the most part, the road signs had either names or numbers and the map showed the opposite.