Rei, I would just like to say that the way you have him set up, and the placement of your hands on his head is very AKC in the first picture.
I friggin love it, LOL!
If at all possible, I think you should pursue a UKC championship with him. He's a super nice animal, and I will admit, he has matured out and developed extraordinarily well in my opinion.
I feel he has a lot of attributes that WL tend to lack. One of the things I love most is his rear angulation, primarily because he has turn of stifle, but *is not overdone*. I CANNOT STAND straight rears. I'm sorry, I can't, I hate them. These are German Shepherds, not Malinois or Chow Chows. Turn of stifle is correct, and beautiful.
I find Trent to be a wonderfully balanced animal, and from the pictures you take, he is quite agile, looks like a fluid, easy, moderate mover, and is the kind of "old style" dog I would be absolutely proud to own.
If I'm going to pick on anything, it's his head...and it's not even really his head. It's his ears. Usually we find our dogs to have ears too big for the head, but Trent has the rare ears that are too small! I would also like a better shaped eye, but that's being super nit picky.
His croup could be a smidgen longer and his tail a bit lower set, but like I told you before, grooming up that croup will help the appearance a bit.
Trent, IMO, is a dryer type dog, but has the coat and muscling to be aesthetically pleasing. I know you think his muscling needs to be better, but for "just a pet", he's way ahead of the game for most dogs.
You got a real good one, for sure