Not trying to diss fashion designers or socialites but would Jan's occupation in comics translate well to the big screen.
A lot of the early women of the marvel universe have had their jobs tweaked to fit a more modern jobs and less 60s stereotypical ideas for the movies:

Sue Storm: actress to scientist
Jane: nurse to physicist
Jean Grey: model to doctor
Pepper Potts: secretary to Admininstrative executive to CEO

Even the Earths mightiest heroes cartoon got around this by having Jan be the youngest Avenger (being a grad college student who works with one of the professors of her college setting grants up for his projects)

I not sure having a fashionista fight battles alongside government assassins, soldiers, mutated nuclear physicist, genius billionaire inventors and other dimensional beings is enough for even the movie going public to follow.

But change that and you change aspects of Jan's personality that make her unique.

Thoughts?