Exactly... I got it all to fit in my Altima, but ended up leaving the trim ring off of the CD Receiver. It fit nicely that way but there was a couple millimeters of space on either side that normally would have been covered by the trim ring. It wasn't noticeable at a glance.

I was gonna cover it with some plastic notebook cover inspired by your trim ring for your sled, but then my wife totalled the car and took care of that problem.