A Maine non-resident CCW permit. They issue at 18, will send it in the mail (from what they’ve told me) and Arizona has complete reciprocity with Maine.
Think again - that won't satisfy the law:
18 USC 922 (q)(2):
(q)(2)
(A) It shall be unlawful for any individual knowingly to possess a firearm that has moved in or that otherwise affects interstate or foreign commerce at a place that the individual knows, or has reasonable cause to believe, is a school zone.
(B) Subparagraph (A) does not apply to the possession of a firearm—
(i) on private property not part of school grounds;
(ii) if the individual possessing the firearm is
licensed to do so by the State in which the school zone is located or a political subdivision of the State, and the law of the State or political subdivision requires that, before an individual obtains such a license,
the law enforcement authorities of the State or political subdivision verify that the individual is qualified under law to receive the license
The state the school zone is located in will be Arizona. You will not be licensed to carry the firearm BY Arizona with a background check performed by Arizona. You will be licensed BY the State of Maine and it will be Maine that does the background check. Thus your Maine license will only exempt you in school zones in Maine. That's what the law states, and that is also the way ATF interprets it:
Link Removed
Did you have a backup plan to comply with the law? Map out the school zones with 1000' perimeters and stop outside each one and unload the gun and lock it in a box, maybe? Just be aware every time you are within 1000' of school premises (not just the building), you will be committing a Federal felony with a loaded firearm.