Last couple times I was there mid-summer, it looked like there were numerous people camping off permit based on how hard it was to find a site.  One trip I couldn't and ended my trip a day early because of it.

That could be part of the reason.

Major road runs along the south side of the lake. Natives pretty much permanently have trailers in the old Odenback Station area where there is a spot to launch a boat. Still one of my favorite lakes in the park. 

This is just my speculation, but I'd guess there are a high number of buffer sites because it's a popular pass-through lake to get in/out of Cedar. Most of the adjacent bodies of water are small lakes and/or river travel with few campsites, so Radiant would be the obvious choice to pull ashore in inclement weather (eg. if you're heading back to the access but don't think it will be safe to cross Cedar, or if you've launched out of Cedar and made it to Radiant and realize you won't be able to make your farther destination). Coupled with the amount of traffic on the lake... cottages, trailers, motorboats... it might also be a popular spot for off-permit camping. Or even if non-campers are just occupying campsites for lunch or a swim at the shoreline, people with a permit could mistake the sites for being occupied. It just seems like a busy 'hub' after long stretches of travel in every direction. Just my guess

Some of the campsites on the north shore have large beachfronts. I don't know about the eastern sites. The west shore are less appealing, based on my own preferences. If you're going during June bug season, the beach campsites might help catch a breeze to help keep the bugs away.

Thank you both for the info. I just checked out #4 and #9 on Cody's website and they do look great!

Cheers, Bo!