Certainly, it would be very possible to write a paper of that length on that book. The larger question is if you can identify a thesis statement based on the story that you are interested in pursuing and researching to that depth.
You could use segments of the novel as illustrations for ways in which the Vietnam War affected life attitudes and actions in the US during the time period of the story. Research regarding anti-war protests and pro-war demonstrations and discussions could be made very relevant to the story.
You could explore the development, expression, and loss of religious faith in relationship to the characters in the story. Examining how different religious faiths respond to the kinds of questions Owen addresses could be another perspective.