Rulertrack with secondary timing apart from Project settings

It would be nice to be able to set a zero starting point for a rulertrack, anywhere in the project disconnected from the project settings. This way i can find the same timecode as my client when he gives feedback to the exported wav/mp3. Because usually my exports dont start exactly at bar zero. Or there are multiple export points in one project. Now i use a videofile with a timecode as a workaround. Or is this possible already…?