Woodtroll,
The Allagash is a great River trip! I would aslo suggest that you might want to visit Baxter State Park plenty of moose there, ask a ranger where and when the best times are to see them. I do not know what they have for Pop-up amenities, I do know they offer camping. On your way up the coast you may want to stop in and check out LL Bean they offer just about everything an outdoors person could want and a short distances from the main store they have an outlet. It has been some time since I was last there.

flp