Paper for Custom Book Jackets?
You might consider Kraft-Tex® Paper.  Many people are using it for bookbinding.  It is also used for making wallets, purses, even luggage.  It is ultra-durable (virtually rip-proof), can be sewn like fabric, and embellished in many ways including printing.  Here is the description written by the manufacturer, C&amp;T Publishing:

Wait until you get your hands on this rugged paper that looks, feels, and wears like leather, but sews, cuts, and washes like fabric. Kraft-Tex® is supple, yet strong enough to use for projects that get tough wear. Use it to bring an exciting new texture to your craft-sewing projects, mixed-media arts, home decor, and bookmaking. Durable fiber-based texture softens and crinkles with handling and washing.
Original unwashed Kraft-Tex® is available in Black, Chocolate, Natural, Stone and White by the bolt or by the roll. (It is now available in several more colors.) So many ways to play with Kraft-Tex®: sew it, stamp it, paint it, fold it, draw or inkjet-print on it. White is a wonderful canvas for painting, rubber stamping, drawing, and stitching. Black makes metallic ink or thread, gel pens, and powdered pigments pop! Kraft-Tex® does not require interfacing.

I have purchased some and can’t wait to see what it is like to work with!