I think it depends very much on the method of navigation. If you are using a GPS-driven moving display with airspace coordinates taken from the AIP/NOTAMs, then that would allow you to get close to the line and be sure of staying the right side of it. Having a recorded trace is a good thing, too.
If you’re relying on the trusty 1/2mil, chinagraph and MK I eyeball, then I would leave a lot more latitude. For starters, how accurate is the map? Is it actually what will be referred to, should you be accused of infringement? The example shown at the beginning of this thread could easily fall under “self incrimination”...