Tony, for what it's worth, over the last few years I've shifted toward milling my own wood for model projects (wood that I've harvested myself), and so far I've found myself astounded by how much model-scale lumber comes out of even a smaller log. My sense of scale is calibrated to firewood and construction-scale lumber (I normally build furniture, sheds, barns, etc. with the lumber I mill here on-farm) and even with lots of loss to milling kerf, I have more model wood than I could ever use just from a couple moderate-sized trees. Granted yours is smaller diameter than anything I've done but even a series of 1' long, 2"x2" blanks will produce quite a bit of thin wood. I guess it depends on what size and type of model projects you're contemplating using this for.
My personal take would be to not worry so much about the minor loss of running a flat edge along one side. You don't have to cut the log in half, just take off enough of one side for a flat stable edge for further milling, essentially what you'd have to take off anyway to get rid of the bark and outer edge. But you also know your equipment and skill set best, so I don't mean to tell you what to do.
Cathead's post in Milling a log of boxwood. was marked as the answer