Need ideas for a better bulk file uploader for multiple files

So here is the situation. I am designing a content management system that handles content for Publishers (Books, Journals, Magazines etc.).

Here are the steps the user will take in my CMS:

1. User clicks on "Create New Book" option
2. The user fills out basic information with regard to the book - Name, Author/s, Category, Fonts, InDesign Master files etc
3. Next, the user is required to create chapters. Now according to my CMS, each chapter is just another file/ folder structure. But in the UI, the files are categorized into tabs - Art, Manuscript, Specs, Misc.

Here is the problem, if the user is only uploading one chapter, then he can just choose the different tabs he wants to upload the files to like so:

But this is going to become tedious for larger books with hundreds of chapters. Is there a better way to tackle this problem?