I got into the scopes yesterday and found them archaic. I spent a good amount of time trying to do the same thing, to no avail. Asking around and I came to the conclusion that the scopes can not be changed or altered.
Only tip I found was to run the scopes on a Reference Window, but there is no realtime scopes during playback.
Best thing I have been told is to make a feature request.
https://www.adobe.com/cfusion/mmform/index.cfm?name=wishform
I am looping my SDI out through my monitor and into my capture bay mac with the BlackMagic PCI UltraScope, and mirroring that video back to my edit bay on the iPad. A stand alone scope would be cheaper (or not), but the capture bay runs all the time, and the scopes take no power to run. Other benifits are that I get scopes in Photoshop, and AE.
I have been doing this setup in FCP for a year now, so it’s just works for me. But, I would love to have better scopes in the application too.