Ok so here is the deal...I just got back from doing my first competition and the wife and I are wanting to do more of them the only thing is the build I did was hell and and a half getting it to and fro. It is a stationary grill that I had to put on a dolly and then on a trailor. So I want to build something that is on its own wheels which isn't the part I wanted help on quite yet. I also need to make it bigger as I had three grills with me and not a one of them was big enough to do what I needed them to. So here is the design I was thinking from the top view and the side. My idea was to use two smaller propane tanks maybe like 250 side by side like a double barrel deal. The firebox on one. The heated air and the smoke comes from out of the fire box and travels under the baffle plate of the first tank and into the second tank through a pipe the same square inches as the fb to cc opening. (indicated in red arrows) the second tank will have the baffle plate opening to the actual cc. (indicated in blue) that air will travel from the second tank back into the first tank through another pipe and out the chimney. I had the thought that the air would cool down way to much by the time it got back to the first tank but then the baffles are gonna be heated heating the air above it. And just looking at it I just had the thought if the pipe from the second tank to the first was just above the baffle plate it would keep more heat in the tanks. What do you all think. Like I said this is in the design stage so far.