I was inspired by the notion of internal vs external stories to look back over some of the agricultural stuff: thinking along the lines that internal stories will be driven by events and practices of everyday life, and what is more everyday than getting enough food on the table.
Looking at the RQG stuff on agriculture that I'd ignored before, I came across this: "A plow requires two oxen to pull. Among most farmers in the Dragon Pass region, only certain people may use the plow upon the earth, most commonly initiates of Orlanth or his son, Barntar the Plow God." (RQG: p177)
So my first thought was: Typical Orlanthi sexists with their patriarchal appropriation of the means of production.
Second thought was: Wow!! What potent mythological significance lies behind that social rule. Ploughing the land: the violent penetration and scarring of the submissive Earth by masculine power, followed by the casual broadcasting of his seed... This is not only about limiting women's access to the tools of survival, this is about ritually re-enacting the rape and submission of womankind. Barntar, you dark horse!
How would your Women's Clan respond to the cultural and mythological constraints?
Do you subvert the social rules (and the narrative) by becoming Plough-women and adopting mythologically appropriate attitudes. (I can plough Ernalda as well as any man...)
Or could you instead adopt a no-plough agriculture that depends on cooperation with the feminine powers of fertility rather than domination? (There is is more than one way to bring a food forest to climax.) This latter option could be something that looks a lot like modern permaculture. But it may also be a more ancient tradition from a time before the windy gods when Earth cults predominated. So as your new clan looks for a mythological voice, it may find it is rediscovering something that has always been just under the surface.
Or, another idea, perhaps you could invert the power relations within in the dominant myth? A shy and timid Barntar cultist has to be coaxed (actually paid!) into action, and is symbolically tied to the plough - now pulled by feminine-associated dinosaurs who scrape Orlanth's brother over the land until the Earth goddess is satisfied.(Yay, triceratops-plough!)
Whatever the solution, women's agriculture offers some interesting opportunities (and motivations) for building the mythological foundations of your clan.