Romney admires Duncan Hunter. After the first GOP debate when asked about the other candidates he only mentioned Hunter and praised him. He said he learned from him.
Which is why, as a conservative, Romney is my favorite of the "moderate-wing" candidates. I think he would handle her royal highness far better in a debate than Rudi, who would be pilloried as a bully.
Romney seems to have the ability like the joke about a great diplomat-- he'll tell her to go to hell but have her looking forward to the trip.