https://www.amazon.com/gp/product/B0036G97DG/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Something like this would be a good option too since the stud/threads are shorter than other kind. The ball is already welded to the threads. Just make sure to use blue loctite and it should stay on real good. Only thing is this one linked is M10 thread instead of M8 threads. I can't find the M8 on amazon for some reason.
I have the bar-end mirrors on my Street Triple R, so I use the 10mm regular mirror port for a RAM mount ball. Easy fit.
Edit: Link, $8 on Amazon.
I personally used that hole as a mounting point for a 360 camera using RAM mount hardware.
Those are the pieces I ordered. The male thread one is the ball and screw that goes into the mirror spot. Then the x arm and the socket arm to attach together. About $50 total when I got it all
RAM Mounts (RAM-B-349) 1" Ball with M10 X 1.25 Pitch Male Thread https://www.amazon.com/dp/B0036G97DG?ref=yo_pop_ma_swf
Ram Mount Cradle Holder for Universal X-Grip Cellphone/iPhone with 1-Inch Ball - Non-Retail Packaging - Black https://www.amazon.com/dp/B0055PH0XA?ref=yo_pop_ma_swf
Ram Mount Composite Short Double Socket Arm for 1-Inch Ball Bases https://www.amazon.com/dp/B005KWPJ04?ref=yo_pop_ma_
I use that mirror mount for my RAM setup, with this base: https://amazon.com/gp/product/B0036G97DG (M10 1.25).
Mount your phone or camera on a RAM mount in it.
https://www.amazon.com/RAM-Mounts-RAM-B-349-Pitch-Thread/dp/B0036G97DG