Having a daughter who is a free lance fashion designer and who has extened her 5 bed house to accomodate a similar trend and the experience of what that has entailed over the years, I would say your basic requirement judging from your initial thread is to reduce the requirement for such a large wardrobe. :twisted:
As Alan says make the most of existing alcoves, in my opinion any division of the space is going to have a far more claustrophobic effect on such a small room than just the loss of floor space would suggest.
Beds under windows can be subject to cold down draughts in winter.
Window seat built as a storage chest can house a large quantity of shoes etc. even if you have some lift out racks to keep them in layers. You will see slim line wall mounted shoe racks in IKEA try and see if something similar can be incorporated in any unused corridor or little room wall space.
Long term clothes storage can be subjected to vacuum packing to reduce volume, slide under beds easily. Alternate summer/winter collections on racks.