Disk plow ash pan would probably have been an easier fix that I did. My original build had the bbq ash pan - and I had temp issues (probably due to damp charcoal - but I blamed the pan for it's up/down airflow. I replaced with a pizza pan - and got better airflow (as the lip of the pan was now below the nipples - air could get sucked strait from the sides to the bottom of the fire). When I switched to the forced air system - the nipple was above the lip of the pizza pan - which caused an uneven burn...
I never thought about just changing the ash pan back to get a pre-made deflector. But deflecting down is even better. Perhaps will try it if I do a rebuild.