I called UA and spoke to a very nice women in Chicago who has been with UA 29 years. She did offer to split the DEN-LIH flight, but said that I would go to the bottom of the waitlist if she did so becuase it would technically be like issuing me a new ticket today.
I realize waitlists are based on status first, then fare paid, then time on the list, but since the DEN-LAX flight now is NF0, I thought I might as well leave the itinerary the way it is.