RE: Lightening the GP Skybolt
I wouldn't hesitate to do both of those cuts.
As you can see in the Ultrasport pics, I removed everything inside the doubler holes.
One word of caution, I wouldn't get too close to the nose... That nose has to bend around to form a curve, lightening holes too close to it can cause problems. So I would avoid any cutting forward of the lower wing saddle.