the grill probably gets 550*- 600* - it's a standard Sunbeam family size gas grill probably medium in size as backyard grills go.
the way I do it is turn the grill on for about 10 minutes on high and than put the pie in its pan onto the stone which sits on the reversed deep dish pan setup I have. With the stone on top of the reversed deep dish pan the pie sits as high as possible in the grill with the lid closed. Actually the top gets done before the bottom.
I then take the pie off the grill, put cornmeal on the stone and put the pie directly on the stone (out of its pan) for another minute or two to finish the bottom to a medium brown crispy consistency.
here is my set up - it's the 4th post in the too much heat topic:http://www.pizzamaking.com/forum/index.php/topic,3328.0.html
Works like a charm