[1.12] adding second layer to entity rendering in code

Hi guys,

In Minecraft 1.7 I had mobs that would wear clothes, that were separate textures applied on top of the main one at rendering time with this code:

@Override
	protected int shouldRenderPass(final EntityLivingBase entityliving, final int i, final float f) {

		final int armourRes = this.shouldRenderPass((EntityLiving) entityliving, i, f);
		int clothRes = -1;

		if (i == 0) {
			clothRes = setClothModel((MillVillager) entityliving, i, f);
		}

		if (armourRes > 0) {
			return armourRes;
		}

		return clothRes;
	}

Basically, a separate model from the main one, just slightly bigger.

In 1.12 I can't figure out how to do something similar. BTW, I can't use layers in the JSON because I don't know in advance (when my mod is built) what clothes will be available.

Thanks!