Is there a way that I can control the maximum number of Visable Skinned Mesh?

Our team is planning to develop a MMORPG with unity3d.

What is my goal is to limit the number of Visable Skinned Mesh inside the view frustum for performance reason.

Here are my ideas:

1. Collect visible skinnded meshes with using OnBecameInvisible() / OnBecameVisible() ( it works perfectly as expected )

2. Using OnPreRender(), I can sort that list by distance. If this list exceeds the maximum limit, I will trun off "renderer.enabled" to hide it.

3. Using OnPostRender(), I trun on "renderer.enabled" to restore it.

I applied my ideas to the unity.

However, the result was quite stange to me.

If you take a closer look at the Statics, the "Visable Skinned Meshes" is 13 but the rendered result has 80 prefabs on that plane.

I am aware that I can use extra camera distance layers to cull them, but it's not I want. ( Imagine that you are playing a MMORPG which has a same respawn position.)

Last but not least, I try to reuse unity's culling system to save per frame performance and also hope to reuse occlusion results if possible.

Could you tell me any good ideas?