Heya, I've been slacking on my play time, OS grinding was driving me mad.
Basically, I killed a LOT of Hijos, and a few of the junk dealer missions. But the biggest help was the mission chain in St. Rose's Bay that gives an item that adds 200 to all your trade faction standings.
The missions start with Sylvia, and end with a job for Maxwell, that gives Maxwell's Letter. It's a mid-20s level mission, IIRC.