I'd think a narrow perimeter of 3M body foam tape around the perimeter of the stick-on convex mirrors (say 1/2" wide +/-) should be enough to get a solid seal on top of the 2020R convex mirrors.
Yeah that was the modification I spoke of. I was just lazy and was ready to ride with them and stuck them on anyway. I check them here and there to make sure they aren't loosening at all, but its been over a month and they are still going strong.
Edit: we will see what happens in this Texas heat in the summer though.