Here's an idea: fill two bobbins or spindles with plied yarn; wind one off into a center pull ball (for reasons that will become obvious, you don't want both on their bobbin/spindle when you do this) ... then use Papuan Thigh Spinning to join the outer end of the ball onto the bobbin. This technique has you roll each single together and then roll the opposite way to reincorporate the plying twist.
Wa-la ... two bobbins full combined into one. Now take the center of the center pull ball, and start winding your mega-skein ... Might work ....
Let me know if you try it, and I'll update this entry when I try it myself!
