We visited this campground over a weekend that was going to be rainy in the Willamette Valley. Sarvice is listed on the Painted Hills park map with plenty of amenities- toilets and showers, mainly.
The owners live across the street, a note on the main cabin said to leave the money ($10 for tents) in a lockbox by the bathroom. There was one other couple each night of the weekend, so it was incredibly quiet and peaceful.
There are perhaps 15 RV pads. They tend to be clustered with 2-3 next to each other, but generally the campground is spread across a hillside.
Amenities- there are a handful of cabins, the RV pads all have power and water (but not sewer). I think the RV pads are where tents are supposed to be- it's basically the only flat ground- but the large rocks mean you'll want a good tent footprint and thick sleeping pad or air mattress). There's a kitchen area with stoves and fridges. I didn't use it.
Obviously this is a "corral", so there are horse facilities. That's all I know about that. I was on a bicycle, not a horse.