I don't really know the audi's internals. But maybe you could mount an amp behind the dash. you could try to unmount the car's carpet-floor where it's mounted on the bottom-side of the dash.
Then there should be enough space where you can mount an amp.
Or try to unmount the glove-box (usually 2 or 3 screws) and behind it you could find some space, too.

I don't know if there's a way to show the tags via the boardcomputer's display. I had the same problem with my peugeot but didn't succeed. But maybe there's someone out there with a working solution..

TeeMcBee
Mk2, # 080000143, 12+30 GB