These are all great ideas, using the sound-bar's speaker outputs and sending them into the sub's speaker level inputs is an approach I did not even consider.
I believe I'm experienced enough to pull this off. Problem is the client would be there watching the entire time and most likely we will have to drill a hole in the sound bar to run the speaker outs... My other concern is how bad will this impact the sound of the sound bar, its already sub-par for such an expensive TV --we can't know until the damage is done.
I used to do this all the time in car audio in the 90's when I was an installer. I do recall being able to hear the degradation of audio--I have to think by now it's better.

Here is the sub we used:
[Link: sunfire.com]


This is not bad either, I think I can just use Snap AV's replica of this amp EA-MINI-3D-35
[Link: russound.com]