I searched for this option for a long time. Silhouette per Object. I now wrote a Script, that uses the RH6 Make2D with hidden lines and grouped. As I’m writing I think it can even be simplified.
As seen in the Screenshot hit “grouped” and “hidden lines”.
Next reference the grouped elements into grasshopper curve component.
Make2DOutlineEachBuilding.gh (19.4 KB)
The script uses a VB Script component from David Stasiuk (https://www.grasshopper3d.com/profiles/blogs/closed-curve-intersection-network)
I hope this is helpful.