Hey. Sorry for taking so long to reply. Did you ever fixed the issue?
Seems not a lot of people are reading this lately. Either everybody is on vacation or this is more of a "cool new factory exhaust upgrade with 1.5 more HP and ipod install" kind of forum
You could cut the knee panel. I know it's a PITA, but there will be a visible cut-line in the middle, or wherever else you cut it at. The middle will make sense because then you could just use a large fender washer on the bolt underneath ash tray to keep it together.
Do you have a Bentley manual for the car? Those are going for $30-40 on Amazon.