see, it wasn't that hard... I used a 15/16 wrench too.
hopefully my posted instructions didn't leave you guessing too much.
The manual states how many turns to give the rear spring to preload it before you move to setting sag by measuring. I forgot what it was supposed to be. did you set it according to that?
Checking sag is super easy.... you just need a helper to hold the tape and read a number while you sit on it.