We combine solar box cookers, retained heat cookers and your Rocket style efficient wood cook stove in a group of what we call ecological cookers. I am very interested in ceramic liner material. You mentioned tree gum. Here in the Altiplano that might be hard to get, but in the valley areas or Amazonic areas it could be another matter. I have pictures that I can email you if you want to keep track of how your seeds are producing fruits elsewhere besides Honduras.
Wood ash is a great insulation.