It would be too easy to see through.
However, if you covered it in moss, it would be much more stable than craft mesh, and just as opaque. It will allow MUCH more water flow than craft mesh, even with a light covering of moss.
You might also consider painting it so it's a more natural color than white. Krylon spraypaint is 100% aquarium safe when applied in multiple thin coats and allowed to dry between. Allow 24-48 hours of drying before putting in the tank, and you might consider a clear coat over it just to protect the paint from scrapes.