Spray and Pray
Find this Clutch Nixon Challenge just west of the Copperhead Rail Yard. Arguably the toughest of the stunt runs- the time is tight, the course is long, and the plane handles like a winged bathtub.
On the fourth marker, don't turn very hard- just enough to slide past the stone bluff.
It's okay to pass through the first bridge marker at an angle- the next target is fairly distant, giving you time to turn,
Don't relax when you see the finish line- it is still entirely possible to scrape a wing against the rock and lose everything.
Finish the course to complete the challenge, and unlock the Stars and Stripes seaplane.