Things I would change:
1. Make the KP extension fit tight to the bowl and lid
2. Make a cover or door, something like the WSM has, to close up the KP so that you can shut down the fire without having to take everything off. I have the steel and its heavy and gets super hot. I don't like to mess around with removing that after cooks so I just let it burn out.
3. The opening height could be a little taller, I'd say to the bottom of the steel roof should still work
I put my kettle lid on just to keep the heat. I'll remove it and close the bottom vents if the air temp gets to hot for my liking. Not to mention, the steel fas 2 large slots in it.
I also use the KP thermometer but don't know how accurate it is. I also use my IR to check stone and steel temps.