6 years is not possible if you are doing ethnographic fieldwork on top of your PhD and you don't already have a fieldsite. 8 years is probably the minimum.
It is certainly possible to do it in less than 8 years. Torres did it in 7 at NYU. 4 years of fieldwork and got a book contract with UC Press, UC President's Fellowship, and a lined-up job at Albany. Murphy did it in 6 at Princeton, got RWJ and is now at an AP Michigan. Jerolmack did it in 7 at CUNY, and they are even less well-funded than Berkeley. I just don't buy this notion that Berkeley students are taking 10 years to graduate because they are all ethnographers (they aren't). It's an issue both funding and mentoring and less with kinds of projects they are actually doing.