They would have worked fine for either the round yakima bars, the square Thule bars or the HD Rhino rack square bars. I have the Rhino Rack HD Vortex bars. . . supposedly quieter than the square ones, and slightly wider than the brackets that came with the tent!
Stopped at the hardware store and they didn't have any precut bar stock that would work as a replacement, so I picked up a piece of aluminum bar stock to cut down and drill. Should aluminum be fine, or should I go with the raw steel?