Mounted a v-lock adapter (male portion) to a old Caselogic hardshell iPhone case with the smallest screws and nuts I could find. Cut out the interior padding where the nuts would go to compensate for the space and further sanded down the screws with a drimmel so that with the removal of the padding and addition of the nuts, the inside of the case is still evenly flat and there's no bulge. Covered the nuts by gluing a piece of plastic that I cut off a piece of packaging, over the screws to prevent them from scratching the phone.
Caselogic iPhone hardcase
or any cellphone hardshell case
The OEM screws are 6 metric and are too close to the windshield, so I used two offset risers attached to the mirrors screws to get about an 1 1/2" out
I drilled several threaded holes thru a metal plate attached to the risers