I imagine you're trying to have this info natively on your driver....but, what I did for this was to set up a CD tracker on the top of the screen of my slaves and crank the UI scale up as high as it goes so you can see it well when it's not the main screen. Did the same with combat text; incoming damage on the top right outgoing top left with max font so you glance down and see what's going on even with the screen minimized.

I am curious to check out some of the raid leader addons for this too. (Exorsus Raid Tools).