Timothy -
Hindsight is always 20/20. your weight loss would have been much less and the treatments a little easier if you had accepted the PEG. Actually, I'm surprised the doctors allowed you to continue treatments while losing so much weight.
Unfortunately, the thick mucus in the back of your mouth / top of throat will remain for quite awhile. If you hydrate enough, the thickness is reduced and it becomes a bit easier to deal with.
If you're not producing saliva at this point, you may have to deal with using alternative sources over the long term.
Recurrence??? It happens from time to time. There's not much you can do about it. Don't skip any follow-up visits or scans. Maintain good oral habits If something changes from your current condition, don't hesitate, contact your ENT and schedule a visit.
Don't waste too much time or energy on worrying about recurrence. Concentrate of being cancer free and living the best life possible.
Good Luck