Cougar Creek is a great site to launch from; easy access to the water and the campsites are nice. It appears to be a well-run site.
We launched from there last year (early September) and it was just getting ready to shut down for the season. We talked to the operator who said it was extremely busy over the summer - 100% capacity - so that might be an issue for you. We were told that people drove in and had to turn around because it was totally full; not sure where you'd go if that was the case.
The road in was a typical gravel forest service road, rough in spots but not terrible; the further in you go, the rougher it gets. However, people bring full-size RVs, trailers, and boats in there, so it can't be too bad. I suspect it might be better earlier in the year, and we hit it after all the summer traffic had degraded it somewhat. For reference, we drove a Subaru Forester; not sure I'd want to go in there with a low-slung car like a Civic or similar.