Coloured sidenote area for Tufte book

Question

I'm trying to have the sidenote (or margin) area of the tufte-book document class have some background colour. Ideally it would cover the whole page, but only those where it is relevant. I have tried several solutions including: How to set colored ruled margins for different pages? and How to set a certain color (other than white) to margin areas? however none of them really work. I get background colours, but at random places, and it does not really account for which pages have sidenote areas or not (granted I could do it by hand in the worst case, but I'm not even there).

For instance once thing I try it that:

% !TEX program = xelatex

\documentclass{tufte-book}

\renewcommand\allcapsspacing[1]{{\addfontfeature{LetterSpace=15}#1}}
\renewcommand\smallcapsspacing[1]{{\addfontfeature{LetterSpace=10}#1}}

\usepackage{geometry}
\usepackage{eso-pic,xcolor,lipsum}
\pagecolor{red}
\AddToShipoutPictureBG{%
 \AtTextLowerLeft{\color{white}%
  \rule[-\footskip]{\textwidth}{\dimexpr\textheight+\footskip}}}

\title{Book title that is long}
\author{Some Auhor}

\begin{document}
\maketitle

Test with some notes\sidenote{Test}.

\lipsum
\end{document}

But the background is not limited to the sidenote area.

I would be after something like this: https://www.principiae.be/book/pdfs/TM&Th-samplepages.pdf.

Is there no hope but to find by hand the right dimensions?

Answer 1

You need calc to get the lengths right.

\documentclass[nobib]{tufte-book}

\usepackage{xcolor}      
\usepackage{eso-pic,picture}
\usepackage{lipsum}        
\usepackage{calc}

\newlength{\marginoffset}
\setlength{\marginoffset}{\hoffset+1in+\oddsidemargin+\textwidth+(\marginparsep/2)}

\AddToShipoutPicture{% 
  \AtPageLowerLeft{% 
    \put(\marginoffset,0){% 
          \color{lightgray}\rule{\paperwidth-\marginoffset}{\paperheight}%
        }%
   }%
}%

\renewcommand\allcapsspacing[1]{{\addfontfeature{LetterSpace=15}#1}}
\renewcommand\smallcapsspacing[1]{{\addfontfeature{LetterSpace=10}#1}}

\title{Book title that is long}
\author{Some Auhor}

\begin{document}
\maketitle

Test with some notes\sidenote{Test}.

\lipsum
\end{document}