Check the throttle valve, somethimes can generate similar noises if the throtle valve is losen in axle. It is tipical for right side, since on the left side is more fixed by TPS.
Can hear it from riding position. Its a pretty feckin unmissable noise.
Besides, hanging down at that speed on clear motorway is fine. Adjusting fog light aim whilst riding is no problem, as is riding with no hands or even riding side saddle. I wouldn't want to be riding standing up with no hands at 90 though.