Hello Benoni blacksmith.
Right now I’m building a charcoal retort that I found on you tube. Justin Jennings design. It ticks all the boxes for me. I will be aiming to fully insulate the burn chamber with bricks or kaowool. I might make a few minor mods as I go. This retort uses all the gas to assist in pyrolysis. I have a background running a wood fire to make steam for engines and emitting smoke is just a waste of fuel to me. That’s why I like this design.