Prusa I3 Pro B "Pertinax" frame top bar strengthening brackets

Since I replaced the Z axis spindles of my cheap Chinese i3 clone against better trapezoid threaded rods, I have two spare wobbly M8 rods which were intended to go into the frame, with the purpose of strengthening it. As the top horizontal bar of those printers is candidate to attaching all kinds of stuff to it, like reels with filament, tools, displays, filament guides etc, the resulting load put on this skimpy part of the frame may become considerable, and may need support. One of those spare