I've found some of the places with low carryon limits (Philippines Air specifically comes to mind) they will weigh things that look like luggage, like any kind of rollaboard, but tend not to weigh reasonably sized backpacks. You could keep it on your back like it was part of you and pretend it wasn't there, and they would too. Everyone was doing this. My husband has one of the camera backpacks with the padded dividers you can move around, not too big but he can fit his SLR, large housing, 2 ports, lenses, 2 strobes, and assorted other stuff and he's always been able to keep it. He checks some heavy/non-fragile things like strobe arms. (The drawback to a backpack is, if they won't let him take it, it's quite unsuitable to check so he'd be SOL. So you want to do your research and feel pretty confident this will be ok.) Another thing we discovered on PA, if they ask if you have a laptop in a bag that is a overweight the correct answer is "yes" no matter what. It seemed like they figured people would have laptops, and there was no way you could keep under the ridiculous weight limit with one, and they couldn't possibly expect you to check it, so there was a sort of unwritten laptop allowance.
Another thing you can do is have a strap on the camera so you can hang it around your neck. You can even take it out of the bag, hang it around your neck while they weigh the bag, then put it right back in the bag and they may be fine with it. When that didn't work once for someone I know they handed their camera to a friend in full sight, then took it back and put it back in the bag after weighing and that was ok, silly as it seems. The vest idea can work too, you could even just wear one as a backup plan and put stuff in it if you need to, if you're anyplace where the "as long as you're wearing it it's ok" trick works.
Naturally, it is important to perfect the art of carrying a heavy bag while making it look like a feather, and also cultivate the proper "this is not the bag you're looking for" jedi attitude.
And watch what's going on with other people as you get there. Maybe even choose a line based on that. Sometimes these things will help.
If it doesn't look like my husband can get away with the camera backpack, he has a old samsonite hard rollaboard bag outfitted with pick and pluck foam that he has checked with no problems. (But then there was the hotel valet that perched it on the tippy top of a luggage cart then took the corner out of the elevator too fast. Camera case almost wiped out a lamp and table. Fortunately I happened to be there to see this or he probably wouldn't have owned up to it, but the hotel wound up replacing a whole set of glass filters because he broke one. Also fortunate we were in a place where you could buy such things.)
