Here is my suggestion, make the back side thinner and smaller, only as large as you need, same with the front but not thinner, just as large as you need. The pins are a great idea, they will probably drop temps a little bit, but if you for some reason plan on making more than one of these and plan on selling them for less than $5000, I would suggest you find another route
I am really interested in seeing what you can whip up.
Can you save that in a dxf or dwg file? somethign I can open in autocad so I can show you what I think should be done?
Jon