When I changed my mirrors they included a tool for setting the fluted spacer. Its been a while but if I rember right set teh spacers with tool then set mirrors. Been working good for 5 years. I do get a little vibration in right hand mirror at 80+
No on the side the bolt is under the mount. you will probably see the stem sticking thru which is why you can not tighten it. the washer will be over size for the bolt shank which is 6 mm 1 mm pitch but it has a large head on it so when you get the larger id washer the outside diameter ends up the same as the bolt head diameter.