Yep, that's what seems to be the idea.

Right now I'm split between renting a floor sander and replacing the
underlayment. The tiny 3x21 belt-sander makes it worse that it already
is...

It's not very clear which side has more nails. Some sheets have more
on the 8' side and others, on the 4' side.

Unfortunately, a stud-finder was not of much help...