Well after some initial success I've been having trouble with that set-up. It's very difficult for me to actually transfer the pizza from the peel to the stone, as there's only a couple of inches between the two oven racks and I have no view in between. One time, some cheese/sauce fell off and the pizza was a complete disaster. Another, the back end of the dough was accidentally folded a bit when I tried to wiggle the dough off of the peel, and obviously the folded parts were not cooked through and inedible.
So I've made two pizzas now using the broil chamber in my gas oven. This is a drawer located beneath the heating chamber--beneath the flame itself, in fact. One nice advantage is that the drawer opens easily and even pulls out, making it very easy to take the pizza in and out. And after setting it to 550 and waiting about 45 min, I was getting a reading of 650 or so on the stone with my IR thermometer (though I have no idea of the surrounding air temperature). My first pizza using this set-up was quite good. I baked it for about 3.5 minutes and achieved a similar amount of browning of the crust as the pictures in the post above, yet the bottom was only slightly charred. The bake seemed even in this regard, it perhaps could have used an extra minute in there to get some more charring. What prompted me to remove it, however, was the presence of some charred spots in the very center of the pizza. This makes sense, considering the oven flame is centered right above the baking surface. How ironic--once I have the top and bottom of the pizza cooking evenly enough, the edges/center get messed up.
My second try was a bit less successful... it took about 4 minutes to bake to a similar result as the first. After taking the pizza out my IR thermometer gave me only 450 for the baking stone, even though it was well above 600 several minutes earlier. My memory on these measurements if fuzzy, so maybe the time elapsed was different, but that temperature drop makes me wonder. The broiler compartment is so small that I fear opening it up to put the pizza in dramatically reduces the temperature. This would explain why the pizza seems heated more by the direct heat of the oven flame (explaining the char in the center) than the air around it. And of course, it being an unfamiliar setup, I was opening the door of the drawer every minute or so to quickly check on things.
I've thought about rotating the pizza several times during baking, but am worried that that process will empty too much heat out of the chamber. I've also thought about raising the stone closer to the flame, (as there is room to do this) but I think that it will only exaggerate the unevenness in the center, even if the temperature of everything else becomes hotter. Another solution I've though of is to put tiles directly on the oven floor, to trap a lot of the ambient heat and better insulate the broiler chamber. But this somehow seems like a bad idea (I'd essentially be placing the tiles directly over the flame, maybe this would impede airflow, etc?). Yet another thought is to go back to the setup from the previous post, but using a metal pan to bake the pizza on top of the stone. The benefits of this would be the obvious ease in transferring the pizza in/out of the oven, and also the fact that the metal pan going between the pizza and the stone would slow the cooking on the pizza's bottom, perhaps resulting in a more even bake.