I hope he is a handy DIY type, cause he is looking at major expense if he needs a professional shop to fix that. It's not actually all that bad, but a lot of labor if you have to pay somebody $85-$100 per hour to do it.
Cut out and replace any damaged wood framing and paneling (inside and out), fit and glue on a new filon skin, and paint it to match. All the stuff can be bought online or locally.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL