Frankly, if Carla wears so much perfume, I'm surprised she can even smell yours.
We had a volunteer who must have literally bathed in White Diamonds. It was so bad that people could tell she had been in the library two hours after she left.
When the Boss says, 'Well, you know how Carla is.' I would respond with something along the lines of, 'Yes, I do. That's part of the problem'.
Unless Carla is an absolute, five-star, cast-iron plunger of an employee who can't possibly be replaced, I'd take this issue as far as it can go. Pushing for a fragrance-free workplace is probably the best solution.