It's boot camp time.
If you can take one or two weeks to watch him
every second that he is out of his xpen (or napping), I bet you anything he'll get it. He's ready!
You can either keep him in his xpen even while you are in the house, which he won't like, but it will only be for a week or two. Or, you can keep him on a leash so he never gets too far away.
One thing I did during this time is exercise Thor as much as possible, so he was usually asleep on the couch while we were home. It's much easier to watch them when they are not moving.
You already have a schedule in place, so if you set him up to succeed, he can get all the way there. Do you treat him for pottying outside? Also, do you clean up his messes with an enzyme cleaner?
I know Tobie can do it!
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Oh, I forgot the easiest way to divide up "territory" - cardboard boxes. No, they aren't pretty, but they are cheap, and they can stretch a lot further than a baby gate.