OK CANMAN1976, By you talking about a 16" round stone I assume your talking about an extra large setup for pizza. I have two large eggs and one adjustable rig setup. Like you said one stone over the other with an air gap (I use the big green egg feet between the stones and up high in the dome is fine as long as it's not to high you need room for the heat to come up and around the stone).
The owner of the ceramicgrillstore.com is Tom or tjv on the forum and his number is (940)387-0100 and his website is http://www.ceramicgrillstore.com/ give Tom a call I have and and found him very helpful. He will ask you what you plan to cook for what you need. He is a great person and wants to be helpful. Tim
Snickers, I like Ripnem suggestion. I grill my chicken high in the dome at 400F dome. I also, like my leg quarters cooked to 200F internal temp. Like gdenby has said they are done at 165F but, I like the texture of the leg quarters better when cooked to 200F IT. It's what ever works for you.
When grilling using a raised grid that is grilling a certain distance from the burning lump. Soooo if you don't have a raised grid setup consider using less lump burning in your egg. Also, if you have a second food grid simply put the first grid on the fire ring than wrap a couple bricks with foil and set them on the grid then place your second grid on that...have fun! Tim