Our daughter neatly solved the problem of dried out white meat by
the time the dark meat is thoroughly cooked to proper temperature.
She used a meat thermometer in the breast area. When it reached
temperature, she took bird out and, (as she graphically put it), gave
it a double mastectomy. After which she returned the dark meat and the whole carcass to the oven to thoroughly cook the dark meat.
She pre-sliced the white meat, made gravy, and gave me the job of
slicing the dark meat. Both white and dark meat were juicy and perfect!
Nice way to avoid last minute carving when there was a lot of family,
and no truly skilled last-minute carver.