Once upon a time there was a version of the theme song to Gilligan's Island set to the music of "Stairway to Heaven." And it was good.
Then lo, the scum descended, and they were called lawyers, and they did smite the artist with lawsuits. But the great Percy caught wind of all and said, I grant thee my permission.
And thus did the song survive to be sung to schoolchildren who knew not Dr. Demento. And it was awesome, dude.