The takeaway from this experiment so far is that, unless you have purebred chickens from a stable line that produces consistent results, using wing patterns or the amount/location of the black is completely unreliable. Both my cockerel from last year, and my chicks from this year, have developed in a way inconsistent with the breed standard (especially how much black they have and where it is). And they have been inconsistent between each other, too - for example, the chicks that had a LOT of solid black on the wings early on, haven't consistently gone one way or the other. I had solid black wings end up male (Blinky) AND female (The Baby), and nice patterned wings end up male (Lemonade) and female (Pooh). So maybe this whole thread is pointless
I will keep updating the thread with pictures for anybody with chicks from Papa's Poultry, or another source where the breed is still under development, if they are interested in following how this pattern develops as the chicks grow.
I will say that there is one thing I've found stands out when trying to sex these chicks, and it was pretty consistent and apparent as early as 4 weeks, when the feathers on their bodies started to come in (as opposed to the wings - forget the wings). The females' feathers had a more broken up pattern to them, like dots or spots or lines across the feather, and the males' feathers had a solid color in the middle and looked like they were outlined with the second color along the edge.
Example - here are the two males. Note the feathers on their shoulders and backs, and the tops of the wings (this was at 4 weeks):
Note the higher amount of detail on the females, even if there's no clear lacing yet:
Even the one that stands out with the black, still has finer detail on the pattern, where it looks more broken up:
Here's a male and a female side by side. Note the wide areas of black on each feather on the male, outlined with orange along the periphery, vs. the high density patterning on the female:
This was apparent as soon as their shoulder and back feathers started coming in. So, I'd say, forget about the wings, and look at the shoulder and back feathers. A lot of people use the breast but the breast comes in later, and by then you have the shoulder and back feathers to look at. But before any of that happened, even the shoulder/back feathers, the combs on the boys started getting quite big and read (Blinky only had wings by the time his comb turned red!) so maybe the good ol' comb is still the best method

It is interesting to look back on the old pictures though, now that I know who's who, and see my theory validated. So that's my lesson. Forget the wings, and look at how the body feathers differ - large areas of color in the males, vs. a high density broken up look for the females.