I wish I knew! It may require bringing a prototype to one of the Guangzhou LV factories. Many of the Chinese suppliers claim to be affiliated with a LV factory, but I believe that the claim is spurious except for Shaly@superalv -- her LV prices are generally significantly lower (and her quality is authentic) that it is possible that she actually does have ties to a factory. However, I have often asked her about some hard-to-find pieces in the past, and she can't source them -- but perhaps if I offered her a high price, she may be able to have a piece made.
I fantasize about commissioning sets of trunks and steamer cabinets, although I would settle for having an accurate Pegase 70, a hat box, and steamer bag made. There are a couple of Chinese suppliers which will custom-make handbags, with a minimum order of upwards of 5 pieces -- I imagine they could do the more-basic and bag-like luggage pieces (not trolleys).