Here are the photos I promised (sorry for the delay - the trip yesterday took longer than expected, and I was swamped at work today - this is my first chance). The axle I picked up was a CCF code 3.31 posi. Hope this helps - please PM me if there are any questions.
Here the wire runs along the right trunk hinge - there are 2 clips on hinge:
Here is routing along the floor - as you can see, excess length was looped (not under asphalt. Speaker wire continues under strip of asphalt underlayment). The strip of underlayment was in addition to the normal layer, which was applied on top of it:
Here is routing into trunk next to speaker wire (car had mono rear speaker):
Here is the view from the trunk - note clip to trunk divider, the wire runs to the clips on hinge.
Here is the routing under the lid to switch. Note that the wire has a plastic sheath to protect it from the hole in the trunk lid to just past the hinge: