Thanks for updating your answer with your diff. Arch really looks great in how easy it was to try that. I'm running Ubuntu and have experience compiling custom kernels so this should be slightly easier to try, thanks once again for such a great reply.

Ultimately, I would prefer that this kind of feature is configurable in userland. Wayland's documentation page mentions that "Data from touchpads showed that almost all palm events during tying on a Lenovo T440 happened in the left-most and right-most 5% of the touchpad. The T440 series has one of the largest touchpads", and this may have been true several years ago, but it's quite common now to have larger and wider form-factor touchpads.