Shadow Catcher catching Self Shadows

I need to catch the shadows of the object onto itself.
I can do that but I have to duplicate the object where one copy is set to INDIRECT in the Scene Layouts and the other is the shadow catcher. It’s all good but the duplication of the geometry costs me around 400 MB and render time because it’s rather articulated.

My question is:
am I missing something or is this the only way to achieve it?

Many thanks!