I have a quad lock, but used this bolt hole ball mount on the left hand mirror mount and the middle length ram arm. https://www.amazon.com/dp/B0012TRIXU?ref=ppx_pop_mob_ap_share
A RAM ball mount with a hole for a bolt is going to be your best bet. Use the mirror mount as your bolt position.
Something like this
https://www.amazon.com/RAM-MOUNTS-RAM-B-252U-2-25-Motorcycle/dp/B0012TRIXU