Not sure why you'd think that'd be unlikely, all things considered. The stuff you touch on about the fall from grace and the road to Damascus I agree with, but the whole thing plays out more like an internal monologue, the narration is Paul's inner thoughts as he comes to terms with what happened, while wandering this 'island' which is scattered with mementos surrounding the incident. I see it all as a creation of his mind as he comes to terms with what he has done, and ultimately is granted freedom from the guilt
Are they inner thoughts or words from those letters to Esther?
They way they are written does not read like thoughts. Some read that way, but others include the narrator doing things already done. All the stuff about his injured leg is a voice from the past.