[Aguila Blanca]

Your link to the Maine State Police web site provided a link to the actual law. And the law hasn't changed since I obtained a Maine non-resident permit many years ago. The law says nothing about allowing reciprocal permits for carry in Acadia National Park, so even if my home state permit was recognized by Maine (it's not) I would still keep my Maine permit to be safe.

If you get busted in Acadia National Park it won't be by the Maine State Police, it will be by National Park Service rangers. And they go by federal law, not the Maine State Police web site.

That's just me. I'm inherently risk-averse, and I'm too old and too poor to knowingly put myself in a situation where I might become a test case.