On the rear, is that just a simple breather or is it a road draft tube? You really need something generating negative pressure for engine longevity. A road draft tube is really an aspirator in that as air moves past the opening, it creates a suction. Obviously, it does nothing when standing still but it is quite effective at road speed. A PCV is desirable in that it does create a suction and, in conjunction with a ventilation breather, does remove vapors. A PCV is not better than a road draft tube other than instead of exhausting crankcase vapors to atmosphere, it consumes the vapors in the combustion process.
If all you have is a phalanx of breathers, then you're relying upon positive crankcase pressure to move vapors out of the crankcase. That's not all bad, it's just the least desirable of the ways to evacuate crankcase vapors since it doesn't move as much vapor. You also have the issue where there is pressure pumping and atmosphere -to include dust and dirt- that can pass through the breathers into the engine. You have to use the same filter quality you use for the air cleaner. That steel wool filler many use isn't doing enough filtering like that.
So, if that rear breather isn't a road draft tube, then, yes, you should plumb in a proper PCV.
