Trunk chop if you must, you can correct issues this produces down the road most likely, but for God's sake don't cut roots now to develop new feeders. I don't know of anyone who has done this and said it was the way to go (I never have).
You've expended a huge amount of emotional capital on this tree, as the lengthy list of posts suggests. I see confusion setting in. It looks like you have free access to this tree, so go about your business and come back next January and give lifting it your best shot. Saw it out of the ground, trunk chop it where it makes sense, then pot it up and see if it lives. It's a reasonably nice tree, probably too big for you at this stage of your bonsai journey but worth the try. A 10-year project for sure.
PM me with your email address and I'll send you my big BC development guide. You may find it useful.