As you all know, FoF supports 2 player mode, 2 fretboards are simultaniously scrolling down, so I thought, why don't use them both in a single song.
The result was the test song "Hangar 18" that I fretted for !!!!10!!!! frets in total.
Here is your keyboard:

This was an example how you should map your keys if possible. Think of it as a 2 string 5 fret guitar, so you have to strum for both strings (Fretboards).
Megadeth - Hangar 18 for "Master Difficulty": Mediafire
OK Go - Here it Goes Again "Master Difficulty" (by Kotti): Mediafire
The first player has to take "Guitar - Expert", the second player has to take "Lead Guitar - Expert".
Video for Hangar 18 (Jurgen plays): Youtube
Kotti plays it himself: Youtube
Create your own songs for that difficulty and give your thoughts how it could be made better in the future.
Have fun failing,
Mon01