Oh man thats funny as heck!!! But in a good way. I just love the simplistic engineering that went into that.
Positioning of a speaker IMO is really only important in terms of forward or back. Meaning, as long as the center isnt closer than the fronts, then you will still be in balance.
Whats more important in your case, and seen from the pics above, is the positioning of the speaker in terms of where its pointing. Meaning, use rubber door stops to ensure that you center remains pointing at your sweet spot.
Your speakers are going to be balanced from the factory so that if its a 2 way or 3 way, horn, flat, baffle, w/e, the sound leaving the front of the enclosure is all timed to leave at the same time. So keep your fronts and center in line with each other in terms of distance from your couch, same goes for the backs. The sub as far as placement goes, does not matter nearly as much as acoustic resonance from ambient object does.