Our Thor is 7 months old. He is completely house broken. We haven't had an accident for a few months. He sleeps about 9 hours before asking to be let out of his crate in the morning.
But we feed the dogs separately and kennel one while the other eats.
We will put him out to pee (which he does) kennel him to feed our female. He'll immediately pee in his kennel. It's almost as if he's punishing us for putting him in his kennel
Ever since my girls were brought home I had a 'zero fussing' policy about any and all accident that happen in their crates.
No fussing, no yelling, no dirty looks - I just calmly clean up the mess and thank goodness they did it in there on the crates plastic liner where it is easy as pie to clean up. I do not 'reward' them for those accidents but I believe they both know that accidents in those crates are definitely not going to get them any trouble.
I slept in this morning. About a good 2 hours later than usual and knew darn well that there would not be any piss anywhere on any floor of mine.
Patience got up at some point and went pee in her crate. Every bit of it caught on that plastic liner and not a drop on MY floor outside of it anywhere. After I took them both to go pee this morning I calmly cleaned her crate and went right on with my morning.
(I do not do blankets or bedding in crates for obvious reasons)
As far as feeding them separately like you describe - Have never done that with any Dober pairs and am on the 3rd set of pairs now. Would be impossible to teach them how to properly eat together if they never eat together. And teaching Dobermans (or any dogs for that matter) to be able to eat together in the same room at the same time is not very hard. Yes, It will require your direct supervision but in short order they will figure out all of the rules you set down.
For me the most important rule is 'no
food bowl sharing'. Each dog has their own particular bowl, in its own spot and under no circumstances will I allow them to get anywhere near the other dogs bowl. (water bowls have never mattered here. a single 'community' water bowl has always been fine. have never seen a dog try to get pissy over water and doubt I ever will) They are not allowed to 'inspect' the other dogs bowl for any reason either during the meal or after. If one tries - I will intervene and put a stop to that right quick.
One of mine likes to hoover her food down and the other likes to take her sweet time. On occasion slow poke will eat half of her kibble and then walk away for a few before coming back to finish it. She KNOWS that no other dog will mess with her food that is in HER bowl because of how those 'food time rules' have always been enforced here.
Both of these pictures come from the same mealtime - different angles but same meal:
Notice that in the bowls is a can of green beans split evenly amongst the girls with a big dollop of canned pumpkin over the kibble and that each girl is sitting there waiting patiently (right there next to
their particular bowl). My girls consider that a 'high value' meal.
They all sat there and watched as I got those meals put together, everybody knows which bowl 'belongs' to them and everybody knows that until they are told they can 'go eat' that they better wait until they are.
Individual (using each dogs name as you tell them they can eat) or community 'go' command - practice with their individual names every chance you can.

No dog butt should move from that 'wait' command until you tell them they can.
There were 3 dogs present for that meal. White dogs bowl was over in a different corner of the room but rest assured she always got fed at the same exact time as the dobie girls.
Similar rules apply to the crates. Each crate 'belongs' to a particular dog and I better not catch the wrong dog messing around in the wrong crate. If one has a beef knuckle (or whatever treat) in her crate and works on for a bit before leaving it for later she can rest assured that I will NOT allow any dog to go in there and steal it.