I'm not speaking from experience just some ideas that occured to me. I saw a post the other day that mentioned using a blanket on a horizontal offset. A UDS may be to hot on the surface for that to be safe, but what about a water heater jacket, dishwasher insulation or duct insulation. Just be sure to handle it carefully to keep fiberglass out of the cooker and your hands.
Jonathan - Blue Weber One Touch Gold, rescued NBBD, Weber Smokey Joe