Could be a rebel who really believes in her cause, thinks she's dying as a martyr to it, and that people will rally because of her death. Then she watches from her cross as the rest of her compatriots are nailed to crosses themselves. There's no one left and on top of that, there are no crowds of angry people ready to follow their example and rise against their oppressors.
This scenario is much like the young men in Les Miserables who throw up a barricade in the street, rebel against authority, and are all massacred. In the book - not the play - the people of Paris are quite indifferent to the disturbance going on in that street and go about their normal lives with little interest. Their deaths are pointless.
The key theme I would use in a crucifixion story of that type is the progressive crushing of the victim's spirit. She would begin by going defiantly to her execution. Her nakedness is a badge of honor rather than humiliating. Her suffering has a noble purpose in her mind, and we experience suffering differently depending on our outlook. For example, the perception of the pain of childbirth, when a mother looks forward to a very positive, desirable outcome and future is much different than the perception of pain for a terminal cancer patient.
As the story progresses, she sees her compatriots put up on crosses too. Her belief that she is protecting them, that her suffering has meaning, begins to evaporate. This is the first major stage in the crushing of her spirit.
And then there are no angry crowds, ready to follow her example. In fact, there are only the crowds of the useless bastards who always come to crucifixions to jeer at the victims and enjoy watching their agony. If there are any more of them than usual, they are there to see the naked woman writhing on her cross. Her spirit is totally crushed; she realizes that her suffering is meaningless.
And without meaning, her nakedness is truly humiliating, her agony is only punishment, and it is horrific indeed.
That's kind of an idea of what I would envision, but there are lots of approaches you could take.