Thanks, David and Cherl D. I fortunately have access to a friend of my aunt's who is also an oncologist, so I ran O'Meara's reaction to Tishler's take.

This third doc backed O'Meara's reluctance to radiate the nasal pharanx. He said Tishler's statement that I would expereince "some soreness in the nose" was really softpedaling the extra discomfort involved. He agreed the origin was extremely unlikely to be in the nasal pharanx. O'Meara described the approach that if there was a 10% or greater likelihood of an origin in a given area, radiate, and the nasal pharanx does not come close to that criteria.

And Cheryl, I did have a petscan which showed activity at base of tongue and none in the nasal pharanx. I have been examined with the endoscope both by my ENT and the team at Dana Farber.
Surgical biopsies of the BoT were negative, so the origin is considered unknown, as the petscan is not definitive enough.