There's not much of an off-roading culture in Maine. There are plenty of dirt logging roads but they are mostly wide and dusty... not really that much fun to drive on except as a way to get somewhere for camping, hiking, fishing, etc. If you have a gazetteer you could pick a smaller road to explore but you are likely to end up at a locked gate or a downed tree. They're not maintained for recreation.

You might have better luck in New Hampshire and particularly Vermont.