There is two KOA's nearby and there is Narrows Too ( really nice) and there is Desert Narrows ( we are currently here) and its ok also. THere is a couple others but dont remember the names. I know one thing this is a beautiful area and Acadia National Park is something to see ( we have been there two days now) and plan on going back. Just a nice area period and the weather has been great!
I would recommend the quiet side of the island in Southwest Harbor. Two excellent campgrounds Smugglers Den {private} and Sewall Campground part of the Acadia NP. Great trails and beautiful views. Very little traffic compared to the other side. You will not be disappointed. Lived there for two years and loved every minute of it.