Let us not forget the great unsung hero, Colin Cantwell. He was there at the beginning and helped inspire the look and feel of Star Wars. He pioneered the technique of kitbashing and was hired by George to design prototypes of the ships while he was still working on the first drafts.
The likely reason Rinzler didn’t include these in the book is that they’re not in the Lucasfilm archive. Cantwell still owns all of his original work for the film.
Here’s a great video interview series with Colin Cantwell about his work and history with the industry.
The Star Wars portion starts in Part 3. Lots of amazing stuff that you’ll find nowhere else, including artwork.