Surface shader, too many samplers workaround

Hey there everyone,

I've got a bit of a problem with the amount of sampler2D's I want to use in a surface shader of mine. So far I'm pretty happy with how it looks.

I'm working on my game that takes place in a mine. The shader is for the walls of the mine. They are tesselated, which might make things more difficult.

Now I want to add resource visuals for in the walls (Gold, Iron and crystal patches). For each of those resources I need albedo, normal and metallic textures. In total I need 15 sampler2D's.

But Unity/DirectX doesn't like that. It says you can only use 16. Now, I'm using 15, but I guess Unity needs some as well...

My question, how do I get around this in a deferred lighted scene?

What I've tried so far:

Have two surface shaders in one:

 Properties
 Tags
 CGPROGRAM
 //Shader part one
 ENDCG
 
 Tags
 CGPROGRAM
 //Shader part two
 ENDCG
 

But this only worked in forward rendering. Not an option.

Then I tried to completely seperate the shaders, make two materials and give the wall renderer those two materials. At first this worked, but when I zoomed out, there was a lot of Z fighting. Also not good.

As you might notice, I'm not the best with shaders. Only just picked them up.

I know I can combine textures, and have already done so with textures that sort of go together. But if I were to combine more, then that would result in pretty weird combinations. (like a heightmap and albedo stitched together)

Thank you for reading! I hope there's a good solution to this.

Dion Dokter