TextureImporter - GenerateMipmaps - MaxLevel

Is there currently a way to restrict the number of mipmaps generated by the TextureImporter? I want to use mipmaps with a TileSheet texture, but it doesn’t work properly unless I can restrict the number of mipmap levels generated (based on the Tile size, rather than Texture size).

No, I think the GPU requires all the mipmaps to be present.
You can either turn off mipmaps or create your own processor to modify the mipmaps.