Change document-wide interletter, interword and interline spacing

Question

According to the 2012 paper Extra-large letter spacing improves reading in dyslexia, some spacing adjustments could make reading easier for dyslexic people, namely

• Add 2.5pt to interletter space
• 3 spaces between words
• double interline spacing

I am looking for a way to set this document-wide. I have found some packages that provide environments to change each of these spacings independently, but it might be bit tedious to wrap everything in three environments, and I don't know how that would work with figure captions, section titles…

Answer 1

With inspiration from this and that I have found that

\documentclass{article}
\usepackage{fontspec}
\defaultfontfeatures{LetterSpace=25, WordSpace={3}}
\setmainfont{OpenDyslexic}
\usepackage{setspace}
\doublespacing
\begin{document}
    […]
\end{document}

does what I want. It works with XeLaTeX and LuaLaTeX, not sure about pdfTeX, I don't use that. it should work with all fonts, too, not only OpenDyslexic, but it seemed fitting. The specific numbers should also be adjusted to the font, geometry…