There is enough money in CFB to make the refs full time employees, with grading systems, rewards, punishments, etc. They should be evaluated each game and then culled by their performance. Give bonuses for proper calls, impartiality, and correct their mistakes. Maybe they even clean the game up a little and greatly reduce things like holding and improper tackling techniques from the game.
If you make it a desirable job with competitive salaries and benefits, you’ll have the best chance of getting the best talent and outcomes.