iphone with cover to griffin tuneflex

I have a nice Griffin TuneFlex in my car. It was designed to work with iPods but I am using it with my iPhone. It worked fine if the iPhone had no cover, but with covers it was too big to fit any of the mounts that came with the TuneFlex.

Link to the item on Amazon
http://www.amazon.com/Tuneflex-Aux-Play-Ipod-Car/dp/B0012IVC74/ref=sr_1_2?ie=UTF8&s=electronics&qid=1283795310&sr=8-2