fake lighting on ios

hi, i am working on an ios runner game targeting iphone3gs+ and my game needs to use lighting for effects. but i am having problems with built-in solutions. here is why:

• my first approach was lightprobes. they are very fast and very efficient. however, in a runner game, where you dynamically create environment from prefabs, lightprobes does not help. because you can not move calculated light probes, even you locate them in a prefab. (i even considered to do a manual calculation by GetInterpolatedLightProbe)

• i can use real-time lights but i think it is a very big impact on fps.

• last, i thought i can write a custom shader simulating light effect on my character by polygon normals facing light vectors that i am manually passing to my shader.

what do you think? which is the right way for the project?

thanks for your comments