Pete:
My listening room has similar dimensions. I have my speakers spaced along the 13' width similar to you , the long wall is fine, allowing enough space behind and nice distance to the listening seat. I'm just not happy with 13' distance, I had rather have more room from speakers to the adjacent wall. I have almost 3' and wish I had at least 5'. Trouble is if you switch walls for speaker placement
you only have 13' listening space and it doesn't leave much room behind listening position.
You sure have a nice arrangement for home theater. Question about your ceiling profile, how does the sloped side effect the sound?
Sorry to take your sale post off track, I really like your speakers, good luck with the sale !