I wouldn't think he would be working on his week/days off hun.
The hours are pretty full on, the work exceptionally taxing. He will need the time to recover and spend with you and the baby. The money is so good because of the extreme hours and demand of the job.
The other thing you need to think about especially if your goal is money, is where he can get a job, and where the flights are covered to/from; or how far the drive is for a DIDO role. Petrol isn't cheap and it is most often at your expense.

Good luck! Being heavily pregnant and having a baby are not easy tasks in a FIFO relationship.