Thanks all! Super happy to have picked this one up, as I honestly didn't even know it was a thing. On the rare occasions I search nickels, I just look for a couple of the stronger FS coins that are listed in the book and if it's not in there I don't know about it. But this one is clearly worth looking for.
I also thought there might be three D's in the mix, but the more I stared at it in a more broad sense it does just look like one extra one. That light bit to the north just seems a little too fortuitous to actually be another D in there, and when I zoom way in on it with the scope it sort of disappears.