Circuitsmith,
The problem with the Matrix IS the camber - as it is specified by the vehicle manufacturer. The spec is about a degree and a half.
My experience says that anything over a degree TENDS to cause tire wear issues.
I pulled out the last alignment report (camber):
LF: -0.7
RF: -0.8
L&RR: -1.5
Rear camber does seem high, but there’s not much weight back there.
And again, the current tires are wearing evenly.
The original tires seemed to change very little during their stay on the rear, the edges wore down while on the front, at an alarming rate.