I can almost guarantee you that I've ridden your route. I've biked to Acadia and traveled there several times, and I'm reasonably familiar with it. If you're coming from New Hampshire, there will be a lot of hills, and 60+ mile days will be really tough. if you're coming south from Massachusetts along the coast, you'll have beautiful riding and can easily cover the distances you're talking until the Maine border, where the hills get a bit steeper but still manageable from Portland to Acadia.

Don't even think about doing it until after April, though. I'd personally wait till June.