I saw the post and got a chill, I'm going to the states to get some gear soon and the last thing I wanna hear on the way back in is "What's in the bag?"
St B, why not carry 2 bags? The sure thing bag; camera, flash cards etc: and the just in case bag; backdrops, extra lights etc.
everything....JUST in case!
aside from cameras & lens & cards, tripod, light/backdrop stands, backdrops, reflectors, umbrellas. I dont use ab's or other lighting equipment, just bounce flash or umbrella if i cant bounce flash...natural light when i can too.