+1 on heat deflector
With all due respect, I disagree with the effectiveness of the T plates. I have found them to be very useful for my 12+ hour smokes. I've found, although that I do have burning wood/charcoal at each end of the T plates, I have no problem managing temperature.
Without the use of something to divide the wood/charcoal, I think you'd end up with a pile of smoldering wood/charcoal and difficulty maintaining a constant temp.
Maybe the T plates aren't the only answer, however I think the use of something to create a way to control the amount of wood/charcoal burns at one time would be beneficial.
But I also make it a rule to not mess with my fire once lit, so I never open the box door, period.
I realize intake/ exhaust directly affect the rate of burn, however the T plates are an effective way to support rate of burn support those variables.