Flattened skinned mesh for shadow

I am making a mobile game and not using any real time lighting but I want to have a dynamic shadow under my character as if there was a strong spot/directional light above the character shining down on them. An old school trick to do this is to duplicate the character mesh, flatten it by setting the transform Y scale very small then render it with all the materials set to black underneath the characters feet. The important thing is that the duplicated mesh uses the same skeleton transform as the original model before being flattened.

I have duplicated the model and assigned the animation root bone to the root bone in the original models skeleton so that the shadow model will update and stay in sync with the character. However, by doing this I lose control over being able to scale the duplicated model and any transform I apply to it gets ignored whether it be to the root game objects transform or the render meshes local transform.

Is there any way to make a second instance of a skinned mesh, maintain the animation update from the original model but be able to apply my own transform to the new mesh on top of the skeletons transform?