I've used a Cintiq for years, and it has the exact same issue with tracking the pen near the edges. If anything, it's worse than the Surface. So it never occurred to me that there might be a solution. Thank you for the link!
Landscape vs Portrait will also cause issues, because the angle of the pen is different, and causes tracking issues. It's imperfect, but I still love how good the pen is on the Surface compared to all the tablets that don't have a Wacom digitizer.