I hadn't quite thought out the thermodynamics of the design I had shown. You are correct that the location of the intake for the rib box that was shown would create uneven flow. Sum of energy in = sum of energy out, so ideally the intake would not obstruct the natural convection through the main chamber. I was thinking that we would use the mounting location shown but tap the intake into the main flue. In other words, the output of the main chamber into the input of the rib box. The only downside is the added pressure drop in this additional "cavity". This should be solved by increasing the systems overall air flow or intake flow into the firebox. We have been planning on adding blowers to the firebox so this shouldn't be a problem.
All theoretical obviously... we've never run a smoker like this before. So I'm unclear of the actual affects of these additions to the basic design of a RF system. We are in need of your wisdom brothers of the smoke and meat.