Off HWY 86, there's a big fuel station/mini mart, that's S22. That's one side of it. If you turn there, about a mile or so, you see the turn ins for camping (1/4 ish mile apart). They will be obvious and have a sign. That side has the obstacle course. If you pass the gas station you can go until HWY 78, there's the other side.
I have never rented anything but, Last time out, I spotted a sign advertising one off 78 and a building on the lake side with a big sign near S22, on the lake side of the road (im a bit foggy on the exact location).
Most of the roads have signs and you can get a nice map of the area. I regularly stay off S22. I go in the 2nd or 3rd turn in, go back a ways and camp. There are bathrooms there also. I have never camped on the other side but drive through there all the time.