Granted, that does mean I have to later clean up and delete the placeholders and replace them with the real units once I'm ready to put them into the scenario (doesn't take much effort to do, but it does take a lot of time and preparation to do), and if I miss any placeholder units, it'll be a little bit ugly (fortunately, that's what playtesting is for; the unit tracker in the military adviser tab is a godsend for this), butstill. The groundwork is there.
I just need to add the units from the other scenarios, and then I'll be golden.