very very careful management called for , this "When outside the house, she definitely has some fear elements that stick out to me as she's barking, her hackles are up and her tail is tucked, she looks like a porcupine" sounds like the dog is dangerously fearful , pretty extreme reaction.
I wouldn't try to "fix" her , she is what she is , a product of her genetics and early socialization.
I would have her kept away from people . No need for her to visit or be visited by people who want to give her attention, which is stressful for her .
When you expect people , put the dog in a crate or safe room , for her safety and security , and for the safety of the people you have invited .
this is a tough one .