Was reading along and had a bit of deja vu 
Was looking for the same feature just last month as a compromise for an original question I had, with all the same concepts as above. I thought perhaps Alt might be a better key modifier for drag and drop though with it representing 'alternate', though not sure if that would falsely trigger the menu which may be an issue.
Agree that if such a feature existed it should ideally replace just the visible cover at the time.