Toggling mouse cursor restriction to multiple monitors (and putting others into stand by)

[THX1138]

I have four monitors but I don't use them all all the time so it's annoying when my mouse wanders to a monitor which is turned off. Is there a way I can toggle a restriction of the mouse to a particular monitor? I'd combine it with a way to toggle the monitor being sent a stand-by signal which I can already do. I know I can restrict the mouse to a particular area or the primary monitor but I want is a hotkey to say that I no longer want monitor #3 in use which would then restrict the cursor to displays 1, 2 and 4 and turn off monitor 3. I previously tried a solution involving disabling the monitors but that causes all kinds of issues with relative positions and even resolutions of all the displays being affected each time.