static mesh to dynamic mesh at impact

Imagine a small town where one house has a fence. For performance reasons the whole town (including the fence) is baked into one static mesh. Is it possible or even feasible in Unity to "unbake" the fence as soon as something is colliding with it, i.e. a car, and to replace it with identical looking fence pieces that have rigidbodies on them to make them move around realistically by the forces of the impact?

 

*bump* Noone?