I did a little experiment, and lifted half of the deck (1 stone) up 2" higher. This brought the deck height down to 7" on one side. I thought that this might work, but actually thought the reason it would work would be because the stone would be further away from the flame, and therefore would be cooler when the probe reached temperature.
It did end up working a LOT better, and had a great pizza with fairly even baking (4 minutes @ 600 F... ), but in the end, I believe the difference is less due to the further distance from the flame, than the decreased deck height.
So next step is to load up fire bricks on the deck (1.125" taller, so 1.125" shorter deck height), and fire brick splits (1.3125") on the ceiling (this part is a little tricky). This will bring the deck height down to 6.57" with hopefully a lot of radiant heat on the ceiling, and fire it up to and see what happens.