I am inclined to go down the same route. At the moment it is though the issue of prioritizing projects - my chain protection works, so the project is down in priority. In any case, my plan is to use an alu L-angle extending from the seat stay towards the seat tube. By the seat tube, I plan to add an alu sheet running down from the L-angle. I might split the sheet into two pieces, secured together with maybe with one rivet and one bolt, to allow for adjustments. My chainring is covered with a Chain Disk.