There's also Rocky Lake public lands. You can camp there and hike the Cutler Coast trail. I've done that trail several times and it's great.
You can camp on the Cutler Coast trail, but there are only three sites, that don't allow fires, plus I'm not sure of the fresh water situation. At this public land, you can only camp at the designated sites, and there's no way of knowing if they're taken until you've already backpacked in. The trail is only 10 miles anyway, but it would be nice to camp there sometime and listen to the lighthouse horn.
The Dept of Conservation has some very nice, free maps for Donnell Pond, Cutler Coast, and Rocky Lake. Some you may be able to print right off the web page.
park finder
And get the Cobscook trails guidebook, there's lots of other short trails around.
When I head way down east, I hit as many places along the way as I can...Great Wass Island is nice, takes you to this place called the mudhole.
If you're headed that way anyway, I recommend getting smoked salmon in Lubec; if the tide's right, the public landing offers a fun view of seals playing in the surf...Raye's mustard mill in Eastport...a nice basket in Sipayik...a trip on the car ferry over the whirlpool to Deer Isle (Canada) or maybe Campobello.
Reversing Falls in Pembroke is fun...
I could spend weeks there!