I just drilled a couple holes, one through a little above midway of opposite sides the pvc coupling, and stick a dowel through it that props over the top of the kettle. It is a keg kettle, and so the dowel can't be knocked off since there is an additional rise of the sides above the kettle opening. Very simple, no metal, works fine. However, I don't like the clogging of the paint strainer bag mesh, and so use it pretty rarely.
I likewise recommend against using galvanized anything suspended above the boil!