I have not done it, from simply a pure volume point of view, I have considered making a wood smoking box to sit on top of my UDS (box just simplifies the use of rods). A wood box would be fairly insulated, so there should be no great heat loss with the increase in volume. I suspect it would not be all that hard to find an economical grid size, but I have mainly wanted to do it to hang sausage for smoking. Pretty sure it would be a simple project to make a smoking box for 100lbs of sausage, but you could probably hang ribs just as easy.