Optimise adding shadows in scene using Unity iPhone

Currently I have a map as shown below with ~1k triangles and a 1024x512 texture, my question is if it would be better to render shadows on it using:

A: A small section of the already added texture with alpha using Alpha Blending like shown at here and applied to the map via a few extra polygons.

B: A small texture with alpha using Alpha Blending and applied to the map via a few extra polygons.

C: A second texture using a layering shader like here.

D: Some other method I have not come across yet. alt text

I would recommend using the built-in Best lightmapping, because it is very easy to use. If you don't have the texture memory available to make that look great, then I recommend seeing if you can paint some shadows that you like into the vertex colors. (You can always use a vertex lit shader on a model, without a texture, as a reference to paint by.)

Also, do note that you're wasting half of your texture space with a non-square image, unless you plan on using it uncompressed.

You may need to bake in a lightmap to use for the level itself, and then use a shadow projector on moving objects.