An electricians 'fish tape' works (on my Casita). :)
It's like a coat hanger, but thin and flat. Sometimes you can find em in the el cheapo tool end cap at Ace hardware, harbor freight and such. This photo is of stringing wire up to the solar panel
<img src=http://www.fiberglassrv.com/board/uploads/3f0dc9d9ab068Casita bench removed.jpg/>
This is the 'fish tape'.......the round thing.
<img src=http://www.fiberglassrv.com/board/uploads/3f0dcba570702Casita fan shroud removed.jpg/>