This is totally my perspective on this situation, but I doubt you’re the last biggest person this surgeon will have, and there was one before you. If that makes sense. Also, do you have confidence in your surgeon and their team? I’m a very blunt person, so I would ask the surgeon flat out, “Are you confident in your abilities knowing that I’m the biggest person you’ll be preforming surgery on? What are your concerns? What can I do as your patient to help myself prepare before and after?” While it’s not your job to make the surgeons operation easier, it is your job to make things easier on yourself before and after. From you previous posts I think you’re doing that. You’re physically and mentally trying to prepare for all that comes with this. I can understand your concerns, so addressing them with the surgeon and letting them know what you’re doing to prepare might help ease your mind.