Blocking the see through gaps only works to a certain degree because the dog can hear & smell, in fact it could make it worse if it's anxiety based because they can't see what they can hear & smell and that can make it more intimidating.
As many have already said, long lead and interaction with the dog, make calling her away from anything rewarding, use the same word and 'pay' for the right action with food. Start with calling away from nothing. Call her when she's just sat or laid down, reward. Then move on to calling her away from increasingly interesting things.
Make everything a trade off, nothing is for free in this house. Want your toy? You sit first. Want your dinner? You sit and wait patiently while I put it down. Want a treat? You give me your paw first.
It creates the situation where the dog checks with you instead of just rushing to get what they want, to see what you want in 'return' for whatever it is they're wanting.
Once that is established then you move on to things that are self rewarding like barking at people going past. You ask them to ignore that urge by providing something better when they 'check in' first. Over time the person walking past is associated with a positive experience with you.
I had a dog that was similar, not aggressive though, but she liked the sound of her own voice and was a renowned stubborn breed. I never did stop the barking completely, as in she did bark on occasion, but if she did she'd then turn herself around and bring herself in without a word from me because I'd done that every single time she barked for months, and for the rest of her life. It's an ongoing process.
And yes at first I did have to be tough and 'drag' her away and wait until she'd calmed down and then reward. The time between it starting and her being calm shortened, and then she would see something bark, look at me and come without being dragged. Then she'd see something and look at me first - and you have to get that bit right with timing and reward the check in before you lose the focus, then she would see something, check in with me and wait until I rewarded - without barking.
I wouldn't say it's hard work, more repetitive and that you need to be consistent, even when it appears you've gone backwards or you've not made any progress. But she needs to trust you before you will get anywhere, to know that what you say to do is going to end up being the best thing for her to do, each and every time.
Good luck!