We came back from there 2 weeks ago, Camps 6 was OK .................let us down once or twice.
Lincoln National park amust, we liked Taylors Landing the best, but Surfleet Cove was good too.
Perlubie beach is great, about 17km from Streaky bay,free and flushing toilets and cold showers, have to camp on the beach, not in car park, so need W4 wheel drive, and find out tide heights too. Its hard to find as road in has changed since Camp 6....maybe go and ask at Tourist info. and get current directions would make it easier, we spent hours finding it ...........was worth it !!!!
Loved Coffin Bay national park, best spot was ...........think it was called Black Spring Camp area. Sandy tracks in, 45 minutes from Coffin Bay itself, pitt toilet but well worth it. Can have tidal water across track and times, we had no problems, let tyres down and were sensible.
Coorong National Park.....Mark point ....no toilet there but a great spot.
Port Gibbon was ok , you could camp at the toilet with the others or drive out along the beach and camp in anywhere which we did. The main issue in October was the wind .........might be a bit less now.
Hope that helps.