[Solved] Quickly/painlessly toggle a monitor on and off, or enforce window open location?

[Quirken]

Edit: After a bit of googling, I found a solution: a program called 'arandr'

I installed it via apt-get, and it will generate scripts for your desired monitor configuration, *including* vertical positioning!

====Original Post====

I have one computer with two monitors, but 3 cables running to them. (One of the cables is for a VM with VGA passthrough.)

The majority of the time, I want the left monitor to be the VM's input (displayport), but sometimes I want it to be the linux host's (HDMI).

The Display applet under system settings is irritating, as my right (linux-host-only) monitor is a vertical monitor. Every time I disable/re-enable the linux output to the second monitor, it forgets the relative positioning and it takes several tries to get it right.

If I just leave it enabled even if the input isn't active, programs will sometimes open on the screen, and I can't see them.

Disper gets pretty close to what I want, but as far as I can see, there's no support for vertical displays!

So:
1) Is there anything like disper that works with vertical displays
or
2) is there a way to *force* all windows to open on my primary display, such that I'll never accidentally end up with something on the secondary display? (This has to be automatic; if something popped up, I wouldn't think to hit a hotkey to move windows, etc)