A great place to grind this out is on the eastern side of the Northwest/Southwest sections (see image for a map)
. I went here prior to completing the Tour of Destruction. At this time, if you drive around the area there will be mobs of bouncers and hairbangers (sometimes just a couple of bouncers) that spawn fairly quick. Of course, you should upgrade the Deuce with machine guns prior to this as it makes it a hell of a lot easier.