This is really close. This link from Purple Park Studios is a couple years old but the principles apply. A number of issues need to be addressed. First, if the feet are going to be showing, the shadows have to account for the difference in height. Second, an image plane has a fixed lighting direction so the lighting in the scene can’t conflict with that or it will look odd. Third, shadows in real life have perspective and this method by itself doesn’t account for that, and finally, any shadows cast by other objects in the scene onto the image plane will be completely flat and destroy the effect. Other than that, it’s perfect, lol. I know it sounds like I’m talking my way out of this, but I’m not. I still think it can work.
https://m.youtube.com/watch?v=-Oj-QhJVA7I
