The kiln design approach seems to be an efficient Bourry Box grate coupled with a tall chimney.
Kiln design seems very similar to Kusakabe. Lots of info in the drawings and sketches.
Building and firing the kiln
But also smoke is inefficient firing, and isn't required for reduction - see also the presentation by the Belgian potter at the wood firing conference in La Borne.
Smoke gets in your eyes - John Baymore