Last year I camped at searsport shores ocean campground and they were having a bluegrass workshop. Im not a musician but it seemed like something that would be worth looking into.

At 6am yesterday merging into the highway was definitely made more difficult due to someone who didn't clear off the fluffy stuff. So you're exactly right, the few extra moments are a courtesy to help others on the road.

Using Amtrak you'll only get as far as Brunswick and if it's the sticks you're looking for you'll still have to drive for a bit with that rented truck. As for times to avoid I guess it depends on what you're trying to avoid. Avoiding cold weather? Don't visit between November and April. Avoiding tourists at the parks? The reverse is true. But as for activities there's a lot to do during every season. Hope you end up coming to visit and having a great time!