This is difficult without a drawing or pic...
Do you mean the gap between 2 plates as in Firebox roof and baffle plate? Cause an inch spacing would work to step down the heat - as long as it can breathe ....
And on the eighth day God created barbecue …. because he DOES love us and he wants us to be happy.
Current smokers: Egor (trailered RF) and Easybake (tabletop pellet drive)