How to set-up marginalia with a variable containing the margins and the book value?

Questions
1

I try to cleanup four alternative layouts for a book with wide margins. I want to set the margins with marginalia, but have the values fixed in one place and used as variables:

#let marginalia-wo-tufte = (
       inner: ( far: 10mm, width: 80mm, sep: 8mm ),
        top: 27mm,
        bottom: 27mm,
        book: true,
        clearance: 12mm,
        )

and then:

  show: marginalia.setup.with( marginalia-wo-tufte)

in the layout function where appropriate.

This seems to work, BUT for the ‘book: true’ value. What should I change to achieve the book (even/odd page) layout?