So, I wanted to be able to mount phone/GPS dead-center on the handlebar... I am that guy. lol
In lieu of cutting the bridge, I found a perfect fitting counterpart on
Partzilla, Honda Part No: 95014-22200. At roughly $23 its comparable to the mounts that attach to the clamp bolts, but this has zero impact on clamp, uses factory bolts and you can use nearly any conventional bar clamp for any device you want.
This part was most recently used on the XR650L but they fit perfect and only issue is they are plain black instead of the sparkle grey of the rest of the CB500.
Since I never found a post directly attesting to this "mod", I wanted to post it up for others to consider.