The more I look at the wrinkle on the half wing, I think if the full wing were on, the top half would be pushing off to leeward and forcing the bottom half (where the wrinkle is) to move slightly to windward, eliminating the wrinkle.

With the half wing setup, you can see the support wires all attach at the very top (what would be midpoint on the full wing) so in the half wing configuration there is no leverage or wires keeping it from bowing slightly to leeward. This is also why we don't run our shrouds and forestays to the very top of our masts, there would be no support to keep the mast from bowing out other than the diamond wires, (not enough) and not at all on a Prindle or Hobie 16.

I think it either needs a stiffer, box type, spar or maybe a wire mounting point down a bit from the halfway point?