@nugger What about building triangles inverted a few feet from the peak to force a greater bend at the top? You could even make a row of them on the top using electrical conduit with zip ties to hold them in place while you’re adding load. A few inches of dowel hammered in to end and drilled through dowel to make a cotter pin setup using zip ties that are looped so that the loops can be turned into a pull point for static load roof shaping. Ends could be crimped to further resist metal sheer.