Hi Andrew,
I’m sorry to say that your suggestion with an inverted eye-tracker will unfortunately run into a few issues with the EyeX controller, and although the idea does solve some problems it will run into others, in particular practicalites like eye tracker interference and certain eye-tracking algoritms difficulties.
However, on the positive side, we are continuously working on improving the eye-tracker performance and we have the ambition to make the EyeX controller work better in the corners for larger screens (like 27″). We will continue to update the core algorithms and controller firmware and we will post here if/when we reach a level where we state that we support a larger screen. So for now, not too much guidance, but hopefully a bit of info on what lies ahead.