Yeah, I eventually realised artwork is only discovered at the driver level, so abandoned that approach.
So I pursued the usage of SVG_SCREEN and converted an overlay to SVG using Inkscape.
Using SVG_SCREEN seems to seriously kill performance, any idea why? The SVG is 14MB but would likely be reduced with an expert converting it.
Is this approach a viable solution to emulating the tablet, or am I wasting my time?