Lamoine State Park is a great option if you want to be close to Acadia but away from the crowds.
There are both tent and rv sites, which are intermingled in the campground. There is a bath house with showers and flush toilets. The toilet area was clean and was maintained on a regular basis. There are multiple vault toilets around the campground.
The sites are in rows, from the top of the campground down to the water. Sites at the top are grassier with more sun, and the sites near the water have more shade. Many sites are not flat and require significant leveling if in an rv. Some sites have more buffer than others, but in general I would not say that there is great privacy between sites.
The sites on the water all have beautiful views. There is no power/sewer/water at any of the sites. There are water faucets around the campground, and a dump station near the entrance.
The park has a day use area and a public boat launch. You could launch a kayak from the park. The day use are is lovely, as is the launch area. The staff at the park were friendly and helpful.
You are about 30 minutes to Acadia, 20 to Ellsworth and 30 to Blue Hill. It is a convenient location that is outside of the crowds. The Lamoine Beach is a 5 minute drive away and is a nice place to walk.