Edit: I’m glad so many of you have had no issues with multiple monitors. My set up is a little unusual (3rd display is an infrequently used large tv hooked through the receiver) and is definitely solveable but will take some effort (and honestly, I’d rather spend my spare time outside or with friends, so who knows when I’ll fix it.)
I’m familiar with udev rules. But it’s going to be more effort to write something that works with everything I might connect to than it is to just run xrandr each time. The way it is right now, it never fails and I don’t have to spend more than a minute tinkering with projector settings when I give a presentation.