Many years ago I used to sail on a line called Sitmar (long since out of business). It was an Italian line and they would offer a cruise free to Catholic priests for doing two daily masses. One for the crew and one for the passengers. On our very first cruise with them we were seated at dinner with the priest for that cruise. He became a life long friend and even married my DH and I. I wish more ships would offer this.
This line had single cabins (very small inside cabins) and that is what they got. He would do a single cruise every year with them to different spots (Caribbean, Mexico, Panama Canal). A reall win win for both sides.