I'm late on this and it's pretty well covered, but just one note on nomenclature, a lot of the nice places to "just go" canoe camp in Maine are Public Reserved Lands -- owned by the state but not managed/developed/staffed as intensively like State Parks. Good examples that have mostly been mentioned are Donnell Pond, Seboeis Lake, Rocky Lake, Nahmakanta, etc. These are well marked in the Maine Atlas, and they usually have a lot of campsites where you don't need a campfire permit (solid triangle in the Atlas).