Interesting - thanks for pointing that out. With one or two wraps, the fattened sheepshank seems to still apply the majority of the pressure onto one strand (and doesn't distribute the load that much). When you expand it to 6 or 7 wraps, it starts to become ungainly.
However, doubling up the bight in the overhand loop is a great idea.
So on the stage where you pull out a bight to wrap around - if you pull it a bit longer, you can double it back on itself. Then, wrap the overhand loop around the (now 4 instead of 2) strands. With this adjustment, I was able to hold my weight with paracord without the sheepshank portion spilling.