@brentwood, IMHO one can only effectively wire maple branches when they are young, supple shoots. They soon become rigid and brittle. For example, roughly around May your tree will have produced new shoots with hardened leaves. You can wire and effectively make the new shoot curl/bend/twist/curl along a trajectory you like. You will need to remove this wire sometime in July and then repeat with the second flush shoots around August. Some rewiring and further adjustments can be done about the time of leaf drop. I like to use Al wire for this. After snapping a shoot or two, I think anyone will have quickly learned how to remove the wire when it starts to bite in. Also, don't forget that a lot can be done with clip and grow - let it grow and cut back after the new growth has hardened.
To your question, yes, I would air layer it as you have indicated. That lower left branch can function as an extension of the lower trunk, but will certainly guarantee that it stays alive during the layering. Nevertheless, you've got several years of growing ahead.
If you are interested in growth speed, grow in a pot not much bigger than the root spread, as too wide a pot will slow down growth above ground. By this time next year, or the year after, the roots will have found the pot wall and will be growing around and down the wall. You can simply pop it out of the pot and into the next larger size, filling the gap with fresh substrate/soil to get the most rapid above ground growth rate. This is what many, if not most, commercial growers of Japanese maples do, but they do it in deep pots. For bonsai, you need to do it in shallow pots or boxes, less than 4 inches deep, I'd say.
You could make a 24 x 24 x 3 inch box, say, and put your tree into it straight away. It will not really get going, though until the roots have pretty much filled the box, which could be two or three seasons from now. Making one 12x12x3 to start might be best, then in two or three years maybe you move up to a 16x16x3 box after having done all the appropriate root work. And etc.
Through all of this your trees (this and air layers from it) will have thickened and you will either lop off stuff that has served its purpose in building your trunks. If you air-layered those pieces you could have an entire yard full of maple bonsai in development instead of just one tree. Personally, I rather like this route for many reasons, not the least of which is that it gives one many opportunities to create the special bonsai - masterpieces are the result of many, many efforts, not just the first or the only try.