be careful on how you look for sites on reserve america for OSP sites. If a loop is first come/first serve and open it will show on reserve america as NOT AVAILABLE. Reserve america ONLY shows the sites you can reserve in advance. So..... in the off season when OSP leaves loops as first come/first serve or a whole campground as first come first serve reserve america makes you think it is either closed or nothing available.
Yes, champoge does have loops closed in the winter as does cape lookout (due to sand and water in the loop in the winter) along with some other parks, but many have only a few reservable loops in the winter and the rest first come first serve. especially along the oregon coast.