Here's an edit: let's stay off of Franconia Ridge. There are plenty of social distance runs out there.
I think my favorite might be the Moosilauke-Tunnel loop on the quiet side of Moosilauke. About a mile at the top of the mountain to see people, but with an early- or late-enough start you could be up there when devoid of others.
Or
this, plus Hurricane-Carriage instead of Snapper, and start/end down at Glencliff to make it 26.2.
Anyway, long term, I have to get to the same time zone first.