I need to dissent from the KISS method (largely because it isn't my time or effort). I think the sketch looks great. The door probably was the major problem with you original build, but I see the rest as possible improvements.
There is a good amount of added work there. I would be interested to hear how much each element is valued after a few uses.
One thing I would make sure of is that there is no way for the ash and what-not to clog the air intake in that position.
Keep us posted.