I would just do it just like you were saying... you want to keep your contours left alone on your jaw.
The thing about male vs female jaw lines isn't so much the angulature as it is more one of the thickness of the bone... From what I can tell, female jaw lines are within 1/3 to 1 inch in bone thickness, while a male's is usually 3/4 to 1.5 inches in thickness.
I can get that the surgeon would want to get as much done in one session as you are willing to agree to, since thats more money in their pocket, but I would be weary of anyone that is pushing for it. After all, you are hiring them, it's their reputation and practice that's on the line, and they HAVE to respect the wishes of their patient/client as per the Hippocratic Oath...