In my essential cabin baggage I normally have less camera stuff (I mean, come on, seven lenses in 21, 28, 35, 45, 50, 75 and 90mm, and three bodies?).
Instead I take a toothbrush, a set of spare underwear and a T-shirt in case I get stuck at a stopover airport, usually a book, and I prefer a laptop to a tablet because you're less limited.
My camera kit on the way is usually either a M5 plus a 21 and 50 (possibly a FED-2 as a backup body), or a Leica R5 with the 35/50/90 combination, or if I feel like I have enough space a 5D with usually three out of a 17, a 50, a 24-105 and a 70-200.
The interesting question, however, is why you take two passports! 😀