I don’t know how well it works with baked lighting (unfortunately I can never use baked lightning since I require dynamic day night cycles in most of the projects I have worked on) but I have seen a similar material as shown above (double sided, Opaque, with Subsurface shading model) and it is working pretty well for sails.
http://www.mediafire.com/convkey/b943/35a1xxdccrnn00mzg.jpg?size_id=5
