Going to try a modified gas grill hack today. Plan to put my 5/8 in Cord. stone down on the grates. The warming rack of my Weber Q320 is just wide enough to span the stone and should hold my Emile Henry stone about 3 inches above. Do I need be concerned about closing off the sides and back (there is little room)? Wondering if just having the top stone will produce some faster, and better tasting, results?