Concur, wiring would be a real hassle and time waster. Clip and grow, splinting and perhaps an occasional guy wire would be more appropriate. There are a bit different techniques for niwaki that are applied for trees on a larger scale. On bonsai we work micro scale.
My experience with working on our landscape trees was I was on top of the game for a bit, then had to focus on my potted trees. Then the landscape trees got established and took off…. and I cut the back… then got focused on the potted trees, then they took off…. Still haven’t given up entirely although it seems like a segue to the movie Ground Hog day at this point.
It might be better to study the principles of niwaki and work on your trees as part of a whole landscape design, using the larger landscape as your palette over time.
If you are interested, there is a book on introductory Niwaki principles by Jake Hobson, Pruning, Training and Shaping trees the Japanese Way that might be helpful to you at this stage of growth in your trees. I have a copy and it’s pretty good with basic principles. Its not extensive on maples, but should be helpful. You can get it used for about 11.00 on Amazon.
cheers
DSD sends