I like to use the decline bench to set up on. The support hand is higher than the support knee, so I feel pretty stable.
Being on one foot and 1 knee keeps me from rolling or twisting side to side to heave the dumbbell and cheat.
Once I'm wedged in there and set up square, the actual row kind of takes care of itself.
I also wear my belt, which has got to look pretty ridiculous. But my back feels good.