Can I make a Drupal Book page parent with no content?
Yes, create a new content type, call it headings, remove the body from it and let it have children. 

see http://yoursite.com/#overlay=admin/structure/types/add

Create the heading content type and remove the body, add or remove anything you want or don't want while your there.

Then see:
http://yoursite.com/#overlay=admin/content/book/settings

Add the new content type to the books modules allowed content types and your done.