While the highest rated Go5 champ could be technically out of the CFP final published rankings as long as according to the CFP they are the highest of the Go5 champs.
For every "contract bowl" (Rose/Sugar/Orange in non-semifinal years) and Go5 contract that ends up being ranked lower than 12 BYU has to be at least 1 more rank higher than 12 to even have a chance...