I am in Maine a lot, my GF lives there and i had a conversation with her neighbor who is a State Trooper about being a non resident and CCW. I live in Mass and do carry in Maine. His suggestion to me was that despite the constitutional carry law he still thinks having a non resident permit is a good idea. His rational is that if you are stopped and you produce it then there is no question that you are not a prohibited person at that point. He did not think that being without a permit would cause any issues per-se but the LTC would just reduce or eliminate any doubt in an officers mind, especially in southern Maine where it tends to be more libtard.