Resolved a long time ago, but I don’t want to leave an empty post.
Here’s a Third Person Blueprint that has the functionality.
Mouse buttons set button-down variables and the camera capture control runs off Event Tick. LMB = Camera Orbit, RMB = Camera Orbit + Player Rotation. Note this setup required changing the captured rotation in Movement Input from Control Rotation (moved down to Event Tick and used only when RMB is pressed) to Actor Rotation.
Super basic, not the BEST implementation, but it works.