Hat - I believe that the driver settings are required by the construction or the printer under the printhead travel area. Whether the driver or printer construction is "at fault" in restricting the use of specific paper sizes is akin to trying to determine "what came first, the chicken or the egg!" You can certainly fool the printer by using a paper size smaller than the recommended borderless size. It would take a bit of initial trial and error to set up your image, but it would be easy to do. You will end up with some ink sprayed beyond the edge of the paper in the path of the printhead nozzles and under the paper path that is not really designed to collect and wick away the ink as well as those areas that are specifically designed for borderless printing.
I haven't tried doing this as the standard paper sizes the printer is designed for are readily available in the US. For custom borderless sizes I print on larger stock and use an accurate paper cutter. It would be interesting to experiment with fooling the printer on borderless sizes by using smaller paper tnan recommended, but I don't feel like testing the printer's ability to dispose of the extra ink at the edge of the custom-cut paper size.
I haven't tried doing this as the standard paper sizes the printer is designed for are readily available in the US. For custom borderless sizes I print on larger stock and use an accurate paper cutter. It would be interesting to experiment with fooling the printer on borderless sizes by using smaller paper tnan recommended, but I don't feel like testing the printer's ability to dispose of the extra ink at the edge of the custom-cut paper size.