I'm thinking of doing the same thing to mine. Where are you mounting the LCQ-1? I'd like to mount it up front, close to the head unit so I do not have to run speaker wires up and down the car.
I have not heard that the rears are rolled off below 45Hz, but I see nothing wrong with using channel 2 for the fronts. You may want to test to make sure the auto-sense turn on works from channel 2 inputs, else you may need to run a separate turn on trigger. I believe the factory trigger is the Yellow-Violet from the radio unit (at least it is on the Sony systems).