I live in Portland and have traveled to Bar Harbor
for work many times. It is a good 3 to 3 1/2 hours to Bar Harbor without traffic. In the fall, route 1 can be slow, especially in some of the smaller towns like wiscasset. Belfast (Maine)
and Camden (Maine)
are both great places to stop. But with seven hours of round trip driving, at least, you wouldn’t have too much time in each place. In Bar Harbor, driving around Mt Desert Island
and the national park is great! Places like Southwest Harbor
and Thunder Hole
are great stops.
Can you do it? I guess, but I think a trip to Bar Harbor and MDI from Portland and back is a full day. It depends on how much you want to explore on foot and how much you want to be rushed. Camden is all little shops and restaurants and so much fun to walk around. (A bit more picturesque then Belfast, which I also like.)
Whatever you choose, you’ll have a great time on the Maine coast! You’ve picked some beautiful places to visit! Enjoy.