If you drive up the coastal road, you'll see lots of what you are looking for. We liked Wild Duck CG (adults only, near Portland, no kids) and Shore Hills in Boothbay for campgrounds.
X2 on Camden Hills SP...pretty town. And there are lots of campgrounds around Bar Harbor for Acadia, which is well worth a visit. We liked Bar Harbor Campground...no reservations, no credit cards.
It's a great area for exploring small fishing towns. Just drive down any of the rocky peninsulas a little off the beaten track.
Fun to have steamed lobster delivered to your campsite. Lots of places do ths. Just ask at the office for a phone number.