Hi @poisonnuke, thanks for your query and indeed it sounds like a interesting project you have in mind.
In fact if you download some of the samples included with the Core SDK @ https://github.com/Tobii/CoreSDK and looks at the ‘streams’ applications,
you will see that the Gaze Data stream is normalised to the screen size producing values in the range (0,1) within the established boundary.
Where the user looks outside the screen will produce negative values to the left and top, whilst right and below will have values greater than 1.
I think therefore these outlier values should be adequate for what you are trying to accomplish, but please let us know if we can be of any further assistance.