The cost may be a stickler but I'd bet Envirolon
Clear Coating Restores and Protects from Vivilon Coatings would do the trick. They did my boat with its companion product Tough Enough
Faded Paint, Metal and Fiberglass Restored and it not only restored the faded fiberglass gelcoat but it acts as kind of a non-ablative anti-fouling too. Great stuff! They put the picture of my boat on their website at
Faded Fiberglass Gelcoat Boat Restoration