As others have said, an 'op-up' is pretty much the only way, unless the FA takes a fancy to you and breaks some rules and moves you to row 6...
Anyway, also depends on when you're travelling - if on the peak holiday days (say Dec 21 or 22 or Jan 2, 6, 7, etc.) you stand a decent chance of op-ups since, not only are you a PM, but Y is almost always oversold on many flights during the holidays and BE is quite wide open.