Ha, that rail height thing is real but I gotta push back a bit on the air blowing over the fire part. If your pot was sitting high in the pan, the blower air was going under the pot and out the sides, not over the top of the coal. Same result, cold fire and clinkers everywhere, but the fix was sealing the gap, not the height itself. Either way dropping it and closing that space is what got you there, glad it clicked.

Been cooking on flat tops for years and water on the grill always made me nervous for food safety and getting the surface temp back up. Spritzing right after the flip makes more sense though, since the top side is still raw and the water pulls heat down into it instead of just sitting there. My worry is the flat top cooling off mid rush and messing with your sear on the next batch. Did you notice any drop in crust or did the 40 seconds come back to you somewhere else in the ticket?