Dear Mr. On-Topic,
I agree with Peter.
I would also think that - if the positioning of the seating DID actually make a difference, you would want to leave it configured in the way you usually have it for viewing.
I don't think you are going to be able to get uniform bass response at all the listening positions because some of them are so much closer to walls than others. I'd think you would have to do multiple sub crawls (as many as you can handle, I guess) - marking various sub positions and then moving the sub to the next listening location.
I'd be tempted to use a 20-80Hz sweep or something like that.
In addition to Peter's astute observation about throwing money at the problem, I just don't see any way to figure this out without you spending an extended amount of time on your knees.
