So after trying a few things I've increased my mids and moved the fade just a tough further back so I've changed closer to your set up.
Surround
Rear fade is centered and just behind the front seat backs so about 20% into the rear foot space.
Treble 90%
Mids 80%
Bass 45%
Almost the same but...
So your setup was a good start for me. After many attempts I have surround on, and the dot balanced left to right (in the middle) but the front/rear sitting in the middle of the front seat headrest line. I found pushing it back further (middle of rear floor) just turned up the sound in the...