Or instead of doing the metal work at the top, you can put a simple deflector in the bottom to guide the heat from the bottom right to the middle of the smoker. (Like in the pic below)
That way the heat goes up the middle through the smoker instead of staying on the right all the way up to the vent or any kind of extension at the top.
You could also move your top vent from back right to back left, like the brand new MES smokers finally are now.
Smoker loaded, and waiting for my AMNS. Deflector in bottom right:
Bear