If your doors were like mine, it's the clear coat that is starting to come off and making them look faded. I scraped the clear coat off my doors with a single edge razor blage scraper. Then I polished them with Griot's Garage machine polish (all three) using a random orbital polisher. Then I finished using Meguiar's Flagship Marine Wax. The doors shine better then they ever have since we bought the Dolphin. Did it three months ago, still look like I just did it. Takes a little work, but the shine is worth it. Hopefully I will only need to touch them up once or twice a year with Meguiar's.
1999 35 ft. Dolphin 5350, F53, Banks System, 5 Stars Tune, Air Lift Air Bags, Koni Shocks, Blue OX TruCenter, TigerTrak track bars F&R, Roadmaster 1-3/4" rear auxiliary sway bar, 2004 F450 Lariat Pickup 6.0 Diesel Crew Cab DRW, 4X4, GVWR 15,000, Front GAWR 6,000, Rear GAWR 11,000, GCWR 26,000,1994 36ft Avion 5er, GVWR 13,700, 2,740 Pin Weight.