[Val-Hi King Timber]

I agree with most of everyone here. Timber doesnt have any food aggression, but I also practice what the OP's suggested. When Timber eats, I slowely drop yummy bits of food in his bowl. I dont really do it anymore, but if he tried to growl at me or one of my kids while eating, I'd start doing it again as a reminder.

As far as the alpha roll is conerned....you'll get plenty comments public or private. But Im not here to debate whats right or wrong.
I just know that it does NOT work with Timber. It may be just fine for some, but NOT for us. It really frustrates him and then he tries to bite back at me as soon as I think he is calm and I let go of him.

And for the zoomies and aggression....That sounds like puppy to me. I thought it was aggression from Timber at first too. That or him being defiant trying to show me who's boss.
Somebody just recently suggested to me when they found out that I walk Timber 2-3 miles a day, that why walk, walk, walk? Spend good time throwing balls and toys. It wears out the energy really quick. Its worked really well for us so far. I dont have a fenced in yard, but we do have a pretty decent sized hallway. I grab a basket full of his toys, stand at one end of the hall and start tossing. He brings most of them back, but some stay at the other end too.
Timber is much more well behaved when he's pooped, but definetly not perfect. Haaa...far from it.

 

[Val-Hi King Timber]

Sometimes we just need other people's perspectives in order to change our way of thinking or they way we normally do things. Humans ARE prone to getting stuck in a rut!
Im glad your seeing some new and different things to do with your dog. Im sure he'll enjoy the change of scenery.
You should however be able to hover, touch, stroke, pet, jump around, have a party...whatever...around your dog while he's eating. Ive had the thought too, that Timber may like some privacy while he's eating. But on the other hand, I like knowing and find comfort in doing whatever I need to or the kids need to no matter what Timber is doing. Even if its eating.
I say just do what OP's have told you here. Feed some from the bowl, then give the rest. Practice slowly adding treats to the bowl while he's eating and so on. GSD's are smart and quick learners. He should pick up what your trying to do pretty quickly. Your goal is that you want him to know that the food comes from YOU and NOT the bowl.