Yeah, this scenario is compromised to say the least. Im with you Rowdy, forget the surrounds.
It can work to at least some compromised effectiveness, if there were two viewers only, and they were sitting in each respective couch as close to the corner as possible. Not that being close to wall boundaries is a good thing, but... EDIT: I take this sentence back. In this case, the surrounds are still MUCH too forward. Strike this from the record please.
However, as you've noted, the surrounds will be forward of LP. Mm. My back row has surrounds a bit forward as well, but it still works pretty decently IMO.
Its just that with 4 viewers, or more, in that scenario is going to have one surrounds be much louder than the other, I think, at least when on either extreme.
The best thing I can think of is just go front three. Not having speakers close as possible, but the opposite: try to make as wide of a front soundstage as possible. The front is really where its at anyways. If you had the optimal stage, you might not even notice the surrounds were missing. Seriously.
Subs? Yeah, it would help if he went nuts. Maybe even some transducers for the couch, such as either Buttkicker or Earthquake units.