automatically add additional space for annotations while keeping layout the same

Question

Consider, I've got a document I am asked to review in a way, that I add todonotes/marginnotes with comments.

Therefore the usual document margin might be to small. Is there a way to just add additional space for todonotes while keeping the documents layout unchanged? I know that there are ways of changing margins, page geometry etc. but is there a neat way, where I just would need to add one line of code in the header, to have wider margins during the reviewing process? That is also important since I do not always overlook all the layout settings the author has made to his tex document, so I am likely to change something when setting the wider margins by hand. Furthermore ideally I would like to not mess up with marginnotes.

So basically consider a layouted letter page document. I just want to add additional space, so have additional space on the right of the letter document.

Is there a neat way?

Here is a minimal working example:

\documentclass{article}
% loads of unknown author specific packages, settings, layouting
\usepackage{todonotes}
\begin{document}
This is some text to review.
\todo{This would be my comment on some extra wide margin just for todonotes.}
\end{document}

Answer 1

\documentclass{article}
% loads of unknown author specific packages, settings, layouting
\usepackage[textwidth=\dimexpr\marginparsep+4cm\relax]{todonotes}


\begin{document}
This is some text to review.
\todo{This would be my comment on some extra wide margin just for todonotes.}
\end{document}