There’s a couple of threads on this already.
Have the Honda tailback and find it is great quality and pretty big.
i have the Shad box that fits to a passenger seat mount for the previous model CB1000R. I hoped I would have been able to swap it to the 2018 model, but it doesn’t fit, and I doubt it could be modified to fit. Shame, because it was a good size for storing helmet and jacket when parked, and could carry a lot of stuff on longer trips.