I have finally completed what threatens to be an ever-growing morph.
The aggregated force:
This aggregate army gives me either:
III/1 Slav: Definitely III1c Southern Slav, and options to combine Vikings or Carolingian period German Knights to cover III/1a. The 1b army Western Slavs are spear-heavy, so probably not those.
III/16 Khazar: Pending the completion of a bolt-thrower and a wagon, only the more mobile options.
I have put together two war-wagons, but I'm not quite happy with them yet. Once I am, the army will also suit III/47 Pecheneg very well.