The KY horse park campground is literally right next to the entrance but reservations my be full by now. There is also overflow camping basically on the fringes of the parking area, but there are no hook ups there. They do have wonderful shower facilities even if it is quite a walk from the boondock camping ... and they weren't crowded. Beware the traffic cops take their jobs VERY seriously, you will not be able to drive up to the showers. I think I may bring a bike this year.
If you look at a satellite image you can see the big sideways "8" that is the campground. The field to the southwest is overflow camping and event parking. tents and some RVs are set up near the eastern treeline. I think I saw some to the west, too but it was too close to traffic for my taste. There is a good slope to the ground there and with all of the traffic the ground could get sloppy.
Directly to the northwest of the "8" is the XC course and west a little farther to the barns and arenas. One of the park entrances last year was RIGHT at the western edge of the campground where it is closest to Mark's Ln.
When you arrive, go past the first entrance even if the cop flags you in, tell him that you're camping and continue to the second entrance for campers.