Hang in there. It will get better. From what I've read, I think you're already doing all the right things...wearing him out before you leave, the trainer, etc.
Your dog seems to fall into the category of "do not let it roam free when you're not around." I do agree with everyone...CRATE. It can't be helped. Some dogs are well behaved from pretty much the beginning like my first GSD. I could leave him to roam freely with a whole cooked chicken sitting on the kitchen counter top and come home hours later and that chicken would still be there untouched. (It's actually happened many times.) Some dogs cannot be trusted alone like my current one. This pup would've eaten the chicken AND the tray the chicken was sitting on. So the best thing to do for your sanity is to keep it out of trouble by putting him in a crate. The crate's not as bad as you think it is. Just think of it this way. 1)You're protecting your home from the destruction caused by him. You could be saving hundreds, maybe thousands, of dollars on repairing or replacing things. 2) what if he eats something that gets lodged in the back of his throat and no one is there to take him to the vet? Or he gets into something that is poisonous to him? In the crate, he doesn't have access to those dangers. And 3), not to mention, he won't bark as much and annoy the neighbors if he's in the crate and away from the windows.
Do you live close enough to home that you can come home during your lunch break and take your dog out? Or is there someone you trust (who can handle a powerful breed like a GSD) that can come to your home and take your dog out for a quick bathroom break in the middle of your 9 hours away? That could help ease your mind of the 9 hours in a crate. If you don't have anyone like a good friend or family member, you could use Rover.com or any other site to find a dog walker. Maybe better to spend the money on a dog walker instead of doggie daycare. Anyway, keep us informed.
I like to tell people Shadow makes poor decisions. At over 8 years old she is crated when alone. I have caught her walking the ledge on the pass through between the kitchen and living room, climbing from my bed to the bookcase under the window, climbing UP the 8 foot bookcase in the office to inspect the shiny reflection on the ceiling, using the table to access the glass doors on the built in that were reflecting sun, sticking her head in a heat vent that she for some reason pulled the cover off of, climbing from bed to dresser to fight with the dog in the mirror and best of all …...using the chair to get to the counter to get to the bakers rack to get on the fridge! I guess because she saw me putting stuff in the cupboard up there and was curious? I know how she did it because she knocked stuff over on the way. I was outside for less then 3 minutes.
Have you ever walked into your kitchen to find your German Shepherd up on the fridge? It is a bit scary.
She is not bad or destructive, just curious and agile.
Some dogs just need crates.