Seems to me like the entire penalty system itself really needs to be rebuilt from the ground up rather than throwing bandaids at specific parts of certain tracks. Penalties ought to be more black and white, if going outside the track boundary or making contact with cars / walls is considered a penalty then EVERY instance should be regardless of how fast or where it occurs. The inconsistency I've personally seen and experienced is probably one of my biggest gripes about the system.
I've always liked the way iRacing does it with fixed penalty points for off track / contact infractions, as well as the driver score based on penalty points accrued vs. the number of "clean" laps (or corners I think?). But they run a very different ship from GT so I'm not sure if or even how a system like that would work in a game like this.