The clip above takes the previous footage and only shows the back wall. I think this works well, although the shadow of the side wall and ceiling should be avoided by removal of these elements from the model. Again, the texture of the back wall is particularly strong, and a neutral surface may work better and act as a “screen” to receive the projection of the moving shadows.
In viewing the cone shadow footage I realised that I need to decide if the projection should just be on a single surface, such as the back wall, or floor. This could use a shadow puppet arrangement, with the camera filming from behind a translucent screen. This could also work for filming the floor – the camera would be under the floor, which would also show the footprints of the forms, as well as their shadows. It would need to be strong enough to support the models, i.e. perspex.