Sorry I just noticed you were talking about the red stripe at the waterline. It does not really change the story though. The original stripe is in the gelcoat. The sun gets reflected in the water and kills the red. Again AWL-Grip is the best paint for this and I would recommend spray-paining to keep the layer thickness as thin as possible.
But for the stripe you have an alternative by using striping (vinyl sticker) to replace the stripe. These vinyl foils are very durable and available in many colors.
Wrapping boats is quite popular for competition boats where they want sponsor names on the hull. For companies that do these things this would be a walk in the park is my guess.
Hope this helps you a bit.