I had overcome this issue by using this code:

Matrix4x4 matrix = ... object's localToWorlMatrix ...;
Vector3 s = matrix.lossyScale;
bool needToInvertCulling = Mathf.Sign(s.x * s.y * s.z) < 0;
CommandBuffer.SetInvertCulling( needToInvertCulling );

Please add a feature that allows Graphics.DrawMesh to flip normals

I am running into a similar issue with a skinned 2d character (polygon planes skinned to joints). Here is an example:

Often, the character is scaled to -1 on X to flip it. The scale happens on the root joint of the character which has no skin influence on the polygons. In this case, all meshes draw perfectly in positive and negative scale space. However, if a child joint which has influence on a mesh is scaled to -1 on X, the affected mesh is drawn in reverse space (the normals are pointing in the opposite direction of the other meshes) - essentially the same problem of backface culling not flipping.