Especially the Nazis.

Timeless quote:

If there’s a Nazi and 10 folks sitting together at a table and nobody says and does anything? There’s 11 Nazis at that table.

It would be fine either way

You should be able to do that with input-mapper and some scripting: https://github.com/sezanzeb/input-remapper/blob/main/readme/macros.md#mouse_xy

Does it need to be fully automatic, or does semi-automatic work for you?

I am using input remapper to automate a few functions of my input devices. It only used it on my Plasma desktop, but it should work in all desktop environments.

Hey OP, I did not read your post but the answer is “hell yes”

Does it absolutely have to be an A5 printer? I recon that this format is not widely used. It might be easier to get an A4 printer + a guillotine paper cutter to cut the prints in half.

Yes