I have a 2" chopped Vintique windshield on my roadster and have the glue-on oval style mirror you mention. It's been glued on for three years (almost 7000 miles) without a problem driving in all kinds of weather.

I recently installed a Bop Top and found that the short post extension was not long enough to get around the blind spot on the side. The solution was to go to the "original lenght" extensions and they work great.

Another problem I ran into was I had only the drivers side windshield post drilled for the mirror mount. My solution was to cut the inside post cover and tig weld a stainless nut on the inside. Then drill and tap the post for the right hand side mirror. I filed, sanded and repolished the stainless post to a better than new condition. It tuned out perfect and saved me buying a new set of posts just to mount the rightside mirror. The inside mirror lines up perfect with the small "mail slot" rear window by just rotating it 180 degrees.