EBramwell, I don't have any vibration in my mirrors at idle, and hardly any going down the road. There is some slight vibration going down a rough road but not excessive. They are a world better than the slide on tow mirror extensions I was using. You might have to recheck the nuts for tightness, 40 ft. lbs. sounds way high to me unless you meant 40 in. lbs. If I remember right they were 6mm studs and standard torque for those is 4 to 9 ft. lbs. I tightened mine by feel.
I'm not sure if I'm answering your control knob issue but I had to grind a relief area in the back corner of the switch, with my die grinder, to clear the rear mirror stud and nut. Before I did that the stud was pushing on the control knob switch enough to push my door panel away from the door leaving a pretty good gap. Everything looks good now.
Regards, Mike.