I love Bar Harbor! Its been many years since I've been there. They have the best Clam Chowder! I still dream about it.
Acadia National Park is not far from there. There are a few campgrounds within driving distance. I never hung there because I was there way before I ever heard of hammocks but from what I remember there are a lot of trees there. fly in from Boston's Logan Airport and land at the Hancock County Airport, located 10 miles from Acadia National Park. National airlines serve the Bangor International Airport, about one hour from the park. Car rentals are available at both airports.
Not sure what the weather will be like. May be someone local to there area can chime in. I think you will have a great time there. Have some chowder for me when you go. Beautiful coast line there as well.