How can I lower Decal draw calls at runtime?

I think this is a quite common issue with decals, so I'd appreciate some optimization tips.

Decals are great for things like bullet holes or for adding that sense of variety into textures and models, but the problem is of course if not handled correctly each new decal can mean an extra draw call.

In my case I am using decals for bullet holes. I'm using a texture atlas which has all of the different bullet holes packed together into a single texture. When I fire and the bullet holes appear at runtime, if I only use 1 material all of the bullet holes get batched. This is perfect, but of course it makes all the bullet holes look exactly the same. If I create one material for each bullet hole (still using the one texture atlas) and simply adjust the tiling and offset; then all the bullet holes now look nice and different, but it creates a lot of draw calls (one for each material obviously). So I'm wondering how can I get the best of both worlds, have a variety of different looking bullet holes but be able to batch them all as well.

I've looked at Bootcamp and the free Decal System and both seem to be creating meshes at runtime, which is a bit beyond my programming expertise since I'm simply using a plane which is positioned and rotated to where the bullet hit. I also can't combine the decal planes since they are obviously dynamic objects. Any suggestions?