There was a CamControl addon which permitted pan/rotate relative to a ship's local frame.
I'd disagree that RMB+mouse is the same in external view as in VC. In the VC, your view rotates your head (effectively radius=0) and your observation position remains fixed; in external view, your head effectively remains fixed and your observation position rotates around the camera focus at the radius 'Dist' displayed in the view info top left.
It's equivalent to the difference between RMB/mouse and LMD/mouse in Celestia, or the Orbit/Look around options in Sketchup if you're familiar with that. Sort of 'Ground Observer Mode for Ships' if that makes sense, or a 'UMMU's-eye view'.
The option to pan straight relative to a local (ship) frame, and rotate the camera about its own axis is something I sometimes wish was available in default camera modes, . It's easily done in Ground observer mode on planet surfaces, but not so easy in orbit. I guess there are issues with the new focus point when you revert to rotating camera location around the ship.