The plate is hanging from two pieces of threaded rod which go up through the vent on top of the grill. There are washers and nuts above and below to keep it tight. It does not move at all when I open the lid and surprisingly the weight is not that noticeable. The one big disadvantage of hanging the plate this way is that you cannot shut the vent at the end of cooking without dealing with some very hot wingnuts on top of the grill. I've settled for putting a stainless steel mixing bowl inverted over the top of the vent to shut off the air flow. The big advantage of using the threaded rod is the ability to easily adjust the height of the plate.
On the down side, I don't feel like I'm getting as much benefit from the plate as I had hoped. I've got it down to within 3-4 inches of the pizza stone and am still not getting the amount of top browning I would like. However, it does seem to have reduced my cooking time by 30-45 seconds.
I took a step backwards last night in my pizzas. I think the problem was that I dumped the rest of a bag of charcoal in and it was mostly composed of very fine particles. I think this severely restricted the air flow. The temp stayed between 550 and 600 the whole time.
The good news is that I'm starting a new bag so I've got nice chunks to put in there.
For my upcoming party, I've decided to bake three pizzas without serving and throw them in the oven upstairs just to keep warm. Then, when the 4th pizza is coming off the grill, I can serve all four at once which will help me stay ahead of the game. I'm sure some here will cringe at keeping the warm in the oven, but I think it will help minimize the time people are waiting.
I haven't been over 700 yet with my BSK, so maybe I need to add some more charcoal??