Sprite Shape used as Sprite Mask

Hi, I am using sprite shapes to create platforms in my level and would like to use them as masks to show blood splatters on them from dead enemies.

The Sprite Mask component ask for a sprite to use as mask. Is there a way to plug in the sprite generated by the sprite shape in there?

To be clear I made this work previously on a tile based solution where each tile has a sprite mask component with same image plugged into the mask sprite:

175393-bloodsplatterworking.jpg

I have now switched to sprite shape tech and would like to have the same effect but on sprite shapes. Thanks.

I have basically the same question, and posted about it here: https://forum.unity.com/threads/2d-sprite-shape-is-out-of-preview-for-2019-3.818799/page-3#post-6869681

Hoping to get a response from Unity, but I did post a basic solution, which is to make a copy of the Sprite-Lit-Default shader and customizing it (and applying it to the material that the SpriteShape uses) by adding this stencil setting:

Stencil {
         Ref 1
         Comp always
         Pass replace
}

create a material using the sprites>mask shader, and make that material the fill material of your sprite shape renderer component.