You want to address two things, work out how to combat fatigue plus how to mininise potential for failure.
I try to adjust to the destination time zone, at least partially, before flying out. My trips are normally 9 time zones west, to I attempt to adjust my sleeping patterns 4-5 hours. On the flight, I wear noise cancelling headphones, ones that cover the ear, as they are more effective. Sometimes I play music, sometimes not. I take two benadryl before the plane takes off, an anti-histamine, but also helps to sleep, which I try to do on the first leg, about 12-14 hr flight. I wear a nice sleep mask I got at REI. I tend to be awake on the second leg, 2-5 hrs. When I get to my destination [say Bali], I allow for 1-2 days down time, eat, sleep, walk around, etc. I don't touch my camera. Often, it's an other short trip to where I'll be staying and diving, [like Tulamben, Manado, Wakatobi, Ambon]. When I get there, it's camera assembly time.
I've a fairly big system, over-sized housing, 2 strobes, 2 large lights for illumination, plus a few extra things. I make sure everything is checked, cleaned and prepped before the trip. If o-rings have to be removed, like for the housing and strobes, I put in plastic bags and stick in the housing/strobe. I keep a checklist for everything I need to do to complete setup. The housing also has labels inside to remind me of settings and what to check, like o-rings. I assume I'll be half brain dead, and try to leave nothing to chance. Before diving, I check the setup in the pool or rinse tank. A salt-water environment is not the place to find a leak. The first dive, I pay special attention to the setup, looking for leaks. I also carry a spare camera and lens, just in case. As my diving is oriented towards photography, a malfunction is a disaster.
If your system is relatively new, practice disassembly, reassembly before the trip. Pack any tools you use, plus extra key o-rings, like for the housing. Assuming digital, make sure you make at least 2 copies of everything you shoot. Use separate drives.
I tend to be a bit obsessive about all this, and have encountered numerous camera problems on trips, including a camera that simply quit working, but nothing that has caused me to lose a full day of shooting. I'm also 60+ and the flights and time change sometimes hit me pretty hard, and I pace things accordingly. Some people adjust easily to the trips, off the plane and ready to dive. Not me.