BoB 1 wheel trailer will pass its load up the seat stays and chainstays, given the thin wall race spec tubes torquing the axle will twist them all the time. has been Known to cause problems on light flexible bike such as your 753 tubed one.
That makes sense, I was thinking of my two-wheel Burley with the flexible coupling. What kind of problems did the torque from the Bob cause? Screwy handling? Alignment issues? Or did the frame just all-out break?