With the 160GB classic I think I'm using shim #4 (I can double check when I leave work), but if the thickest shim still isn't tall enough you could probably add some tape or something to fill the gap. The main concern is to try to keep the bottom of the ipod resting on something so as to not put pressure on the dock connector or have it bounce loose while driving. As for CD7-12, I'm pretty sure those aren't supported. I think you just get 5 playlists on CD1-5 with CD6 playing the full library. It will also continue playing whatever happens to be playing when you dock the ipod, so what I typically do it keep it on CD6 and get whatever I want queued up manually before docking.