That’s a good question. I really can’t think of anything other than making a low-poly retopo object to unwrap the UVs.
In the Shader Forge, in the section on ice and gemstones, it is explained how use scaled coarse noise textures to confine the effects of other procedural textures to certain parts of a model; maybe review that section and see if you can figure out a way to apply that to the model you’re working on. Best I can think of right now.
