I thought you only used it as a grill? Anyway, Horizon makes a deflector plate for it. Kinda pricy, but it fits. You should consider taking some aluminum flashing and lower the exhaust to the grate level, though that will decrease capcity. I am not a reverse flow expert, but I'm not sure how well that would work considering the placement of the exhaust. Doesn't the exhaust have to be closest to the firebox for reverse flow to be effective? NB used to advertise putting racks in the bottom of the cooking chamber, below the main racks to increase cooking capacity. Not sure how else to effectively increase, it's pretty tight in there.
dmp