Here is what I did. I kinda did this as a temporary solution but it works good so I haven't improved on it yet. The MIG welding wire works good because it is thin and retains it's shape. I just hang the transmitter over the wire before I hang the 2x4 onto the lip of the barrel. I have an adapter ring inside the top of my barrel for the Weber lid, so there is a small crevasse to hang the wire loop into.
Not sure how a WSM is set up but this works for me.