Just got back from another trip to Council Lake, WA. Arrived on a Tuesday and left on Thursday in the middle of November, and had the entire campground to ourselves. We didn't even have day use visitors or motorcycle riders pass through the whole time we were there. 

The place was reasonably clean, with just a little trash left around some of the sites. Roads were still easy going, but it snowed maybe an inch the night before I arrived. And if my memory serves correct, I think they close the main access forest road NF 23 as soon as snow starts to accumulate.