Under IATA rules, cheap seat passengers like me are allowed to take as carry-on one small bag, a briefcase or laptop computer, a camera and an umbrella.
So... I take my cameras, lenses and one flash in the bag (small rucksack), my laptop, and housing with dome port attached and a camera and lens mounted in my hand... and I check the rest. If challenged I simply say it is a camera and offer to take their picture.
That way when I recently went to the Maldives and my bags went to Thailand, I could still get some pictures.
It works for me!