If you only used to copper to change that one color, you can't get smaller than 8 low-res pixels width of the virtual pixels. You can, however, use more bitpla

If you only used to copper to change that one color, you can't get smaller than 8 low-res pixels width of the virtual pixels. You can, however, use more bitplanes and then use both the copper and cpu at the same time to get more colors, but you'd be tight of bus cycles pretty fast and I doubt you could get more than 80 colors per scanline using this technique.