I did some upgrades to my 2008 AC with Bose (non-navigation) and thought to share my findings to help others out; all in one place.

Aftermarket radio
I highly recommend you find a radio that has 4v preamp outputs. I tried a radio with 2v preamp outputs and the sound output is not optimal; bass is low and you will need to crank up your aftermarket radio to max volume to help improve the sound quality. Not good. Get a radio with 4v preamps and you will vastly improve the Bose setup. I kept the Bose speakers and amp; I just changed out the factory radio because my LCD display was going bad.

You will need the Metra 70-7553 harness and SCOSCHE NAA2B Antenna Adapter

Backup camera

The reverse wire is pink/black (located in the trunk / rear driver's side); black wire is ground

Steering wheel controls

I was able to avoid using the ASWC-1 adapter. Doing this will allow you to use the volume +/- and search +/- on your steering wheel; you will lose the BT phone feature but my aftermarket radio already provides the hands-free feature.
key 1 goes to white/green (factory harness) pin 6
key 2 goes to grey/blue (Factory harness) pin 16
ground the blue/black (factory harness) pin 15 to just the black wire from the aftermarket radio, labeled ground

Amp Power Wire
I ran the power wire (8gauge) through the door grommet on the driver's side. This is the best way, IMHO, without the need to drilling a hole through the firewall, snaking the wire through the firewall grommet, or trying to find the available grommet through the passenger side (behind the glove box).

Hope this helps. Thanks!

Here is a video. Hope this helps!

https://www.youtube.com/watch?v=iq7_xi67dKQ&t=27s