I could add another slot but it's not an easy change, it would require source changes in both the client and server that isn't a problem, but also database changes which I am trying to avoid until I fix some existing issues.
But as Mythos said, pretty much everything made with Artisan is tradable and all the recipes and materials are tradable, so it could easily be assigned to a crafting alt. It's kind of heavy on the inventory for all the materials so would probably make more sense to do that anyway if you already have 2 other assistant skills hogging your bag space.