So you think that growing out a solid trunk, then spending the next few years butchering the roots annually ought to help build good branches? It's an experiment I've been looking to conduct on some of the long-internode-types I've got floating around.
There's a lot of questions to the top and bottom "mirroring" theory....
I believe the tree always want to mirror.
But of course our actions make this impossible.
I believe the more drastic our actions, the longer it takes to return to mirrored.
Resorce!
So your plan sounds good except you should use time and observation carefully while in the ground to whack roots and build a good surface rootage.
Then this is where building branches and mirroring come into play.
We have to take into account what we know about trees. The drip edge is real and a tree knows where its roots reach. If a tree is in a small colander, it knows. If the roots are constantly air pruned the nodes semi-reflect it over time.
In a Proper Colander, branches should build easy with this airprunedness.
I think this time in a colander should be spent building your fine feeders and branching. Slow growth, close nodes.....
By the time it reaches a bonsai pot, it should have little room or need to throw long roots.
So if you can get it to this stage.....
Already built with a fat feeder Block and tight nodes...
I think this is the beginning of a "sustainable" tree with long internodes.
Sorce