I am using very similar setup to 8:1 referred to but have replaced centre pulley on 2:1 with a hook which I can detach from mast. I only need a small amount of downhaul travel to go from Max to Nil so my 2:1 ropes are short, I would not be able to attach pulley to sail if 2:1 rope was captive. A picture will explain it better.
Darryn