Yep. A detached display will let you do exactly that.
It'll be easiest to open the detached display using MC in Standard View, position the display onto your external monitor (send it fullscreen) and then just leave it there. MC remembers the display size (including fullscreen/not status) and position of the Detached Displays even when you close out of MC totally and re-open it later. Then, switch the main UI of MC into Theater View on your Touchscreen display.
In fact, you can have MULTIPLE detached displays if you set up additional zones. Each zone gets its own.
Theater View (touch optimized) isn't really ideal for acting as a controller for things like scrubbing playback and whatnot though. It works great for picking and choosing media, and for navigating through a Playing Now list, but the one problem is that with a Detached Display, you don't have access to a scrub bar over the video like you do in Display View. This is generally good (usually if you are using a detached display, you NEVER want to see any UI chrome there).
I haven't really tried using Theater View to scrub through video with the Theater View Playing Now "dot scrubber" on a touchscreen. I bet it works, but probably isn't ideal for a touch UI (I could be totally wrong).
My plan is similar, though. I want to get a Touchscreen Windows tablet and use Theater View on it (running in "tremote" mode to control another instance of MC on the other machine) to control the detached display on my Video Wall. The tablet I have now is old and uses a resistive touchscreen though, so it is a fairly bad example and I haven't really even tested it.