On the outskirts of this former insurgent stronghold, Munir Ibrahim Ismail and his family have taken up residence in an American military latrine. They picked up the trailer full of toilets at a junkyard for about $5,000 — less than it would have cost them to build a real house — and set to work. They tore out the toilet bowls and scrubbed the trailer for days with disinfectant. They ripped off tiles, poured a concrete floor and added a window. They erected a divider to create two rooms and tacked on a concrete kitchen at the back. Presto! A...