I believe the Kurds are fully capable of patrolling the northern border of Iraq...in fact, that part of the country is relatively quiet these days.
The long southwestern border adjoins Saudi Arabia. I doubt much patrolling needs to be done there.
It is the borders with Syria and Iran that are problematic.
The quicker the Iraqi security forces become fully operational the better. They will, undoubtedly, use whatever measures they deem necessary to secure their country against terrorist threats from outside their borders, employing methods that would leave our political leaders breathless.
We need to train them, get them ready to assume those duties, and THEN get out.