Is the purpose of elevating to tray to get it off the solid surface so air can get into the bottom, or is it to actually raise the heights to get in into an existing air flow pattern? If it is the first, I assume you would not want something solid, you would want something like a small cooling rack raised an inch or so. If is the second, then a solid surface like a brick should be okay? And how high do you need to elevate it? And if there is a natural draft, does orientation matter? I put mine in with the burning end towards the door -- would it work better with the burning end towards the heating element?