As far as leaning back I guess I should mention I am throwing slightly uphill, maybe 20' uphill. I've got a pile of wood I'm aiming at that a range finder said was about 450, I'm coming up short by 20-40 feet and want to be able to reach it eventually.
Knee generally feels good, I did tweak it last winter playing in a tournament where it was like 12 degrees cause I never got warm and wasn't pivoting on my heel well. That being said the main soreness I get after long tournaments is my Tensor fasciae latae, I do a lot of foam rolling my hips.
Schusterick is definitely my form inspiration, I think that's what I was closest to when I started so I've tried to tweak it closer whenever I've watched myself. I was always more inclined to do a stride/walk x step and most other big throwers do a hop or a full run up which always knocks me way off.
I think I can begin my work in a couple changes, I want to stay up on my left toes instead of dropping my heel, and shortening my strides some, see if that helps keep my hips forward and not lagging behind everything else. Schusterick definitely seems to be skipping over that foot during his step, his hips don't drop during it at all.