Pack light. Many of the internal flights have strict limits. Also, my carriers have only allowed soft sided luggage. I opted for a normal Rucksack with lenses and bodies in Lenscoat pouches. I have travelled with two different kits (1) Canon 5dsr + 5d4/ 100 mm macro, 100-400 mkii and (2) Sony a7r3 + a9/ 90 mm macro, 24-105 mm and 100-400 mm. In my carry-on I have a rolled up small Deuter sack that I use during the day.
The mirror less system is lighter and quality is equal.
Dust is your enemy. I chose to have high MP and crop rather than use teleconverters. Do remember a couple of clean microfiber cloths, lens cleaning fluid, lens paper and sensor blower. I always have a couple of black waste bin liners with me for protection against rain or dust storms.
A monopod might be useful but I have never found room for one. Forget a tripod. It will just annoy people on the vehicles. You can fill a sock with breakfast oats as an improvised bean bag ... but many places have bean bags available.
Chargers and adaptors! If you are taking two bodies, chose ones with the same batteries. No 1dxii and 5d4 combination here. Take a couple more batteries than you think you need and charge them when you get the opportunity. Power outage is not unknown. Remember, on international flights the batteries have to be in hand luggage not the hold. If you are flying through JoBurg at any point, only take a penknife or a bladed tool if you have checkin luggage. Otherwise you will lose it. That are not allowed in carry-on within the airport.
I like to work up as I travel, so I can also fit in a Mac Book Pro (13”), backup hard drive and card reader.
Finally..... have fun. But be warned, it is addictive!