Help with name spelling!

We found out we are having a little boy! The only name my fiancé and I can agree on is Callan (pronounced Like Alan) we don't want people pronouncing his name like Caylin or Collin so we were considering these two spellings: Callan and Calhan (which I'm afraid will turn into the hard mispronunciation Cal-Han). Which do you think distinguishes the correct pronunciation more? I'm torn! Also open to other spelling ideas!