4 12s that is my opinion if you wanted it. Limited space with a lot of power is a simple decision for me, increase # of coils and use smaller subs. Cone area isnt as much of a factor as many people think. What is important and you have already mentioned is the enclosure design. If you are doing a flat wall in a small car 4 12s will fit nicely to one side and leave plenty of room for a port.
Also just so you know when i ran 16 volts and a single Stetsom 7kd it pulled 810 amps of current clamped 10,450 watts on 4 lv5 12s with a score of 159.5 dB. This was in a musical setup as well. In my case i know i would have been louder running XLs but at the time the XL had not been invented. So my bet if 160 is your gold do 4 XL 12s.