Hi,
Provided your oral surgeon has carefully assessed your suitability for twilight sedation, it should be relatively safe. All kinds of sedation do carry a small level of risk. Using twilight sedation to help you relax sounds as if it might be helpful, especially if you have a strong gag reflex and may be subconsciously tensing up. I’d ask if she is reasonably confident this will work. Is there another oral surgeon at the same practice who can give a second opinion, especially if she hasn’t tried this approach before?