Kevin what are you talking about, you know very well that Single Din to Double din is VERY doable on the A3s, and has been done before or did you forget??
I personally did it over a year and a half ago, best mod to date. i run the Alpine IVA-W200, with full speed I-Pod connection and Alpine full integrated Black Bird Nav. All controls are through the touch screen never touching the ipod or Nav units themselves.
Here is a Detailed DIY with pictures outlining the conversion, as well as the Ipod install. Includes all Part numbers and CAD retail pricing from nearly 2 years ago. US cars will require the passenger air bag button as suppose to a second blank.
Link to my DIY