A friend of mine have come up with a way to make hanging rods for the 3D, I just haven’t made them because I don’t make sausage that often. So, I just use the racks and lay them. I think there are rods sold on the site you can purchase. But, I can’t see why you wouldn’t be able to hang and control your temps.
There should be a heat deflector available as well, or your idea with a sheet pan and then frozen 2L bottles are other ways people on here have helped with cold smoking cheese.
Hope that helps a bit.