Thank you so much. Looks like two promising leads.

Regarding this request: How would a student go about finding this sort of information outside of Reddit? The internet is full of resources, but how can a student find a person for an interview, with in depth questions?

I can think of two people to call on. James Kirby Martin of the University of Houston wrote what's the current go-to book on Arnold and his treason. You can find his page on the University's website, including his email, here.

Other good doors to knock on would be the West Point Museum and Saratoga National Battlefield Park. You might have to call both places first to figure out exactly who you can email at each (should be the Curator of History at West Point Museum, at least).

PM me if these don't work out and I can ask some of my other contacts in academia.