Order post type by sum of two custom fields

Yes but not in an easy simple way via the order parameters.

I would suggest that you:

  • Maintain a 3rd post meta
  • Whenever you change the first or second, add them together and set the 3rd meta to contain the sum of the new values
  • Order by the 3rd value

The alternative is to write your own SQL query from scratch and all the horrors and disadvantages that come with it