The devil would be in the details, of course. It would probably be difficult for a Kurd to 'pass' as a Sunni Arab. The Afghanis have had little problem picking out the 'Arabs' amoung them. Iraqis can similarly distinguish non-Iraqi Arabs the instant they open their mouths I'd guess. In our cultural ignorance we wouldn't be in a position to 'judge' how good our facsimile really is. Still, I think that you have the nub of an idea there.
Not a problem - Egyptian Jews are indistinguishable from other Egyptians - Yemeni Jews likewise - would Afghans know a Kurd from a Sunni? - would Sunnis know a Govt. Afghan from a Taliban Afghan? - or a Hindu Pak from the other (only eat rice - bad stomach) - Kurds could recruit Sunni in their area, claiming they were trained by Sod 'Em to speak like Kurds - it would destroy Alky Duh and all of their cohorts in a year......
Helloooooooo DoD! Come on down!