BS”D:
Mazel: I don’t think that the book you quote has to do with Tznius:
Daughters of Dignity: African Women in the Bible and the Virtues of Black Womanhood [Paperback] Laverne McCain Gill ?
If you are talking about Sefer Ba’akavot Rochel, it specificly states it’s both a hashkafa and a halacha book, and the two always get confused (as per the author’s ideas, not Hashem’s) to make a book like this practicly worthless for halachic purposes (not haskafic, but hashkafa (especially for tznuis) is variable).
Yeshivaguy1: The book you mention has been quoted to possibly Over the Issur of Ba’al Tosef (way over my head, just a quote from a Rav) and was strongly suggested by many (including my Roshei Yeshiva) NOT to be used (due to it not being normative halacha). I wouldn’t worry about it. In fact, I am currently attending a weekly shiur in which one of the focuses how it is Assur to “go machmir” in these issues, and the bad things that the Rav himself has seen occur due to being Machmir beyond the levels of halacha required in Innyanei Tznuis.
This does not take away from the issue being discussed here (short skirts) which is a (halachic) problem. Perhaps if you see a girl like this a woman relative should offer to take the girl shopping (and pay for it) and buy tznius & stylish clothing. I can’t imagine a girl who would turn down an offer for new clothes.