I've been trying to get monitors to work correctly in any distro of linux since Softlanding (up hill both ways, get off my lawn). You can find many of my rants over the last 15 years or so on usenet, blogs, ubuntu absolute beginner forusm, every time a new distro comes out and I try and get it, and even today the monitor handling is worse than Windows 95 was back then.
The closest I ever came was using xrandr in 10.04, so that's my answer and suggestion - just read as much as you can find about xrandr.
IIRC I was able to rotate a display and had an immediate gnugasm, but then the other monitors stopped working right - what gets real fun is if you want to do something seemingly easier than a Thesis about hardware drivers in FOSS like just changing which port displays are plugged into. Just don't. If you have a working set up, this will dick things up into perpetuity.
Just give in, be happy with just the one monitor.