Yes the little filter would work.
On the stock setup the air comes through the MAF then splits off and goes into the valve cover into the engine then out the PCV valve back into the intake; that way the already metered air returns to the intake but filled with the oily by-products of the crank case.
Now that you have vented the PCV valve that system is no longer "closed". Since the engine is always under vacuum, theoretically, air is being sucked into the vented PCV valve up through the crankcase and out of the valve cover then enters into your CAI after the MAF. Now how much air is making it in could be very small but its probably there none-the-less and filled with oily residue.
I'm sure you'll get it setup the right way. Looking forward to see if there are any gains.
2004 SVT: bewst'd!
2013 Escape SEL 2.0 Ecoboost 4WD
2004 F350 6.8L V10
1986 XR4Ti 2.3L Turbo, 15 psi