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Autozone sells 3M double sided tape (really just a solid strip of adhesive) that's about 1/16" thick and available in a variety of widths.
Prep both surfaces by cleaning very thoroughly with alcohol (swabs/pads from the drugstore) and then apply an adhesion promoter (bondprousa.com/bondpak adhesion promoter pen) and let it set up.
Perform the above and attach the mount in warm weather only and let it set overnight.
The only caveat is that this is the one shortcoming of this type of mount. They've been known to fall off.
There is an arm type mount that clamps to the mirror stalk and places the detector in the same position as the stick on. But they're having growing pains as well.