How to get 'Scale/Fit to page' behaviour automatically when printing?

Question

I have slides created like this:

\documentclass{scrartcl}

\usepackage[T1]{fontenc}
\usepackage[american]{babel}

\KOMAoptions{paper=128mm:96mm}% like Beamer
\usepackage[includefoot, left=5mm, right=5mm, bottom=3.5mm, top=4mm, footskip=4mm]{geometry}

\begin{document}
foo
\clearpage
bar
\end{document}

When printing, the slides only cover a small region of the (letter) paper. What I would like to have is a 'Scale/Fit to page' behavior without having to specify it in the PDF Viewer. Note sure if that's doable, but I thought I'll give a try and ask. So is possible to 'fake' a more standard page size so that a PDF reader believes that the paper size is larger than it is so that printing works correctly? (I looked a bit around hypersetup, but that can only open/display PDFs in a certain way, printing is not addressed).

On a higher level, the question is: Why not simply define a larger paper size? I tried to do that but failed (I used anyfontsize but did not get larger font sizes). Also, this would require to hard-code/adapt the paper size all the time if one wants to print to another paper size... Not sure if that already means that this problem can only be solved on the level of the PDF viewer (?) by choosing 'Scale/Fit to page' before printing.

Answer 1

I finally found a solution. Indeed, no LaTeX-like solution is possible for all paper sizes without recompiling the document. What one can do is to run pdfjam, for example, to do the 'scaling' after the PDF has been generated: pdfjam --letterpaper --landscape --outfile bar.pdf foo.pdf works well based on the input PDF foo.pdf.