You can paddle into the Morrison Run campground. It is accessible only by boat or by hiking in several miles on the Morrison Trail. No electricity or anything, first come, first served.
Or if you can get a reservation at the Red Bridge campground (Corps of Engineers), it has electric, water and bath houses. Also has primitive campsites. All of those spots are not far from the water, but there are several right on the lake. But they are hard to get right on the lake, if you don't already have them reserved. If you stay at the Red Bridge campground, be sure to eat at Bob's Trading Post and get an ice cream cone there also. They have fabulous Chicago DeepDish Pizza. Burgers not bad either.