Hi Paul,
Welcome to our community, unfortunately dubbed the club nobody wants to join. You are getting some emotionally charged advice from people that have had many struggles and seen many friends get taken out by this dreaded disease. I am sure no matter how tough the treatment, each of us would do it again in a heartbeat. I hate to quote statistics but...80%-90% chance of getting it all versus 10%-30% if you don't.
As my otolaryngologist put it, he has seen in the past 5 years especially that with or without the neck dissection, radiation combined with chemo has shown to be the most effective weapon. I had two lymph nodes light up on the PET/CT scan and did not have the surgery. Knock on wood...8 months post treatment this week. I am still just as nervous as the day they told me what I had and I stay up all night before exams but I have had many nights to get to stay up!
I am sorry you have to go through all you have gone through and maybe even more. I don't wish any of the treatment on anybody, unless it extends their life.
When in doubt, get a second opinion from a comprehensive cancer center.
Ed