The cover is none too large. Before it was squashed, there wasn't any margin at all. Post-squashing, with the cover wrapped tightly around the spine of the reader, there's about 3/16" of leather sticking out past the edges of the reader.
I originally planned to cover the inside of the cover, with something like ultrasuede, to give it a neat finish while protecting the reader from being scratched by the washers. But the washers don't touch anything but the skin, and with the skin to protect the reader I'm OK with them touching.
Here are photos:
