ARFoundation- simple baked shadow for placed object

A search turns up a few options for creating shadows in AR.
In my case I simply want a baked shadow that my placed 3d object will cast on whatever plane or real world object I place it on.

What is the best way to achieve this in ARFoundation when using the LWRP?
Could anyone share their preferred method?


One thread mentions using a 'shadow' shader from the ARkit plugin but that doesn't work with the LWRP.

Here is another option https://forum.unity.com/threads/lwrp-receiving-shadows.591595/
but I'm a total shader noob. Can anyone help? How do I use a .hlsl file with LWRP?

 

just cheat it with a plane and a texture with alpha channel

 

For this we're still waiting for ShadowsOnlyPass.hlsl shader in this thread: https://forum.unity.com/threads/lwrp-shadows.652024/#post-4450555

 

What does this mean? Add a material that is 100% alpha but somehow receives shadows?

 

No, bake a shadow in external renderer like Arnold and apply to underlying plane.