This was my second time going to Seawall campground, I had such a great experience last year I wanted to go back! I love the back-country feel of the hike-in campsites (loop D). For stargazers, the short walk across the street to the beach will give you some unbelievable views of the milky way when the night is at peak darkness. 

A short drive to the main part of the park & far enough away so that it's not crowded during busy weekends. Just remember to bring a ton of bug repellent, or opt to go during the months where bugs are less mild.