Is this the only time that she barks or does she also do this indoors or when riding in a car?
Is she getting enough physical and mental stimulation? How long ago did you adopt her? Does she have an enough command that she listens to 100%? Can you call her off when she is barking (ie: is she responsive to you)?
Is she simply barking or when you say "charging" do you mean that she is running back and forth, barking constantly? If so, I would consider that barrier aggression/frustration more than a "alert" barking.
I personally wouldn't continue attempting to "claim the area" in front of the fence... Dogs who are so focused on their trigger will likely find your presence rewarding ... While you are trying to let the dog know that the fence is yours
- the dog is likely to ignore you completely or be REINFORCED unintentionally or it becomes a game of trying to evade you and get to the fence... Not to mention, that most dogs learn that when you aren't in proximity they can revert to barking/charging.
I do not see a problem with using your body as a barrier/interruption between your dog and her trigger but it won't work alone IMO.
Since barking is a self-rewarding behaviour, I wouldn't let her outside unsupervised - you don't want her to continue practicing the barking.
I personally would use positive reinforcement because instead of focusing on what you don't want, you are focusing on what you DO want from your dog and rewarding heavily for appropriate behaviour.
First, I would suggest you shape a "call off" cue - one that means "run to me as fast as you can because great things will happen". You need to have a reward ready that your dog LOVES. You will need to train this cue away from her triggers first and slowly add them. This will help you when you start adding triggers and it will also help you manage the situation when necessary.
While you are training a call off cue, I would take her to the fence and have a volunteer walk by. Reward her the instant your friend walks by and continue to do so until your friend is out of sight (even if she is getting a few barks in). Do this a couple of times and she will start looking to you instead of barking. At that point, ease up on the rewards - now you only reward if she is actively engaged (ie: run through OB commands)... If she reverts to barking, you can ignore or use your body to interrupt or use a no reward marker (which indicates that she made the wrong choice) - when she looks back at you reward. It won't take long for her to realize that barking isn't as rewarding.
You can also try big-time desensitization (borderline flooding) where you have a lot of her triggers walk back and forth constantly, regardless of what your dog does. While flooding is not something I generally like, it is what I had to with my friends Std. Poodle as nothing was as rewarding as barking and anything I did only reinforced him. I let him react and did nothing, I asked my volunteers to keep walking back and forth, acting like the maniac poodle did NOT exist. Eventually the Poodle realized that no matter how much he barked, nothing changed at that point he stopped for instant and I marked and rewarded. He gave up on the barking and engaged with me. While there was is always a tendancy for him to bark whenever he heard or saw something it was 1-2 ALERT barks and then a call off had him running back to me.