Welcome to the Maine thread, Opie! Wonderful to have you here (and in Maine)!
And you are very wise

We planned for about 18 months before getting ours. And things still didn't go according to plan, not even close! But we would have been in a much worse situation if we had just "jumped in."
I think most of Maine is overrun with chicken predators. We have bears in our town (I've found their poop in my yard) but thankfully I have never heard anyone speak of a bear that developed a taste for chicken feed (or chickens) around here (northern Waldo county). We make sure to leave no feed in the run at night. A determined bear is almost impossible to deter. The only ideas I've heard of to beef up a run against bears are very expensive and involved. Ask your neighbors if they've ever heard of anyone in the area having bear trouble. Hopefully not. Our approach has been: "We love our girls, but if a bear decides to try to get in the run or coop, there is very little we can do." Apart from trying to scare it off in the act, of course...
It sounds like you've got a lot of wild country around. That helps. Left to their own I think bears really prefer to avoid people. It's only when they learn human activity can lead to easy treats that things start to go bad.
In my immediate vicinity we've heard of flocks being decimated by foxes, coyotes, weasels, and mink. Less common are reports of hawks/eagles, and raccoons, though those tend to pick off individuals rather than entire flocks.
We have at least one large pack of coyotes whose territory surrounds our land. I've found lots of their poop in my yard, too. Additionally every bird of prey you can think of (even osprey) are frequently overhead at our place. So we opted for a run constructed post-and-beam style with a rigid metal roof and clad in 1/4" hardware cloth with a 2 ft HW cloth skirt around the perimeter to deter diggers. It's not impossible to break into, but even the hungriest critter would probably find it not worth the effort once they started to try.
The degree of protection you'll want depends on the number of birds you have and your chicken keeping style. Ours are our babies; layers "just for fun" that get full retirement. That's pretty unusual around my area. Most people I talk to are pretty
laissez faire; they let the chickens free range and simply buy twice as many as they want... They assume they'll lose significant numbers to predators.
While I could never take that approach, I am a little envious at the relative lack of effort they put into housing chickens
Again, welcome! Hope you have lots of fun here!
Oh and love the Miss Prissy avatar