Multiple Holes with Depth Shader

Hi,

I am making a multiplayer game where players can create holes in the walls, after experimenting with render textures to see trought the holes, I am trying to use the depth mask shader.

http://wiki.unity3d.com/index.php?title=DepthMask

It look exatly the way I want but to make the depth mask shader work, I have to change the material render queue. The shader make that if a material has a render queue higher than 2010, it will not be rendered trought the hole. The problem is that, if there is another wall with a render queue >2010 behind the portal (a wall with another portal on it for example) the second wall is not rendered trought the first portal.

When I make a hole in a wall :

If I make a portal on the ground on the other side of the portal :

The ground get a render queue higher than 2010 and the depth mask shader don't render it.

Thank you.