Surroundbar w/rear speaker question.

Crusher063

I recently bought a Surroundbar and installed it, and it works very well. However, my receiver (Panny SA-XR57k) has a hookup for rear wireless speakers. I'm thinking the RM-7s would be a nice option, but should I go with one or two of the satellite speakers, or get a center channel speaker and use it as the rear channel? My space is limited, so if I did two rear speakers they'd be placed pretty close together, which is why I'm thinking a 6.1 option would work just fine. Thoughts? Does the Panny wireless module recognize 6.1 vs. 7.1?

Thanks!