How to modify the total width in a tufte-book using includemp?

I'am working on a tufte-book document class and I want to change the size of the page. As the page are smaller, I want to fix the total width of the text (including the marginal notes). In the presentation of the document class, it is specify to use the geometry package.

In the documentation of this package, it is explain this operation :

width,totalwidth : width of total body. width=hlengthi or totalwidth=hlengthi. This dimension defaults to textwidth, but if includemp is set to true, width > textwidth because width includes the width of the marginal notes. If textwidth and width are specifi ed at the same time, textwidth takes priority over width.

This is the text in my preamble :

\documentclass[symmetric,justified,marginals=raggedouter]{tufte-book}
\usepackage{microtype}
\usepackage{calc}
\usepackage{geometry,afterpage}
\geometry{papersize={16.8cm,23.7cm}}% <= it seems to be OK
\geometry{textheight=18.6cm}%text : 132 *186 mm <= it is OK
\geometry{width=13.2cm}% <= The code doesn't take into account the marginparwidth and the marginparsep

\begin{document}

\end{document]


I don't know how to precise that includemp is set to true. Who can help me ?