It is definitely doable and even passable, if you can manage your time between work and study. Many of the people around the world take 3 papers in each sitting. And many of them pass in a first attempt. So, if you have a strong determination and can manage your study as efficient as possible. Then, go for it. In your case, you take F5, F7, and F9. All of them are theory and calculation. So it is still OK as long as you have a good time management.