The hell I do. The only thing I can figure out that is as secure as I like is cutting bandits from the herd to the point that there is no chance of interference, or booming and zooming.
What helped me a lot was when I would drag someone out for a 1v1, I would make an effort to "keep tabs" on someone else near me, even if it was another friendly, while I fought my opponent.
Also, get a little "risky" when you cut one out. Try to increase the likelihood of "interference" by not dragging him out quite so far. Or reverse into the fight while another red guy is still barely in icon range. Learn to watch the second bad guy while you fight the first guy, and learn to kill quickly, before the second guy can get there.
Try to increase your SA in "baby steps". You can't really make these opportunities arise, but watch for them and take advantage of them when you see them. Accept that you'll die a little more for a while, in return for developing a skill.
Make a huge effort to not let the guy you're fighting keep you from being aware of what else is going on around you.
Make sure you quickly scan behind and around you a few times in a fight, even when you don't need to. Maybe just once or twice at first. Then add a scan or two, and quickly you're beginning to really get somewhere. Do it in a 1 v 1, even though it's a "waste", because you'll learn to do it, and to still keep track of your opponent, or reacquire him after you take you eyes off of him. Do it when you
can at first, so that it becomes easier to do it when you
need to. It gets easier, and it gets easier to grab more information from a casual glance. It also becomes a habit, and quickly you'll find you're watching around you while fighting, and you don't even realize it. I laugh at myself, because I can't stop scanning while in a fight, even while I'm working 1 on 1 with a student in the TA. There's no way I'm going to get "jumped", but the habit is so strong I'm watching for the bad guys anyway.
Is that guy you're fighting not a terrible challenge? Maybe he's new/inexperienced? Use that opportunity to scan! Nobody else to watch/keep track of? Then pick an object (a barn? a cove?), and try to remain aware of it's relation to you as you maneuver.