One thing you are missing:-

Most airlines will allow you to have a fairly reasonable camera bag and a small carry on bag - about 600mm long 300mm wide and high for all your carry on stuff thats not camera ie a light jacket, book to read and your duty free grog.

I travelled to the UK with BA and home from Paris with Air France change to QANTAS in Singapore (all QANTAS code share) and not once did they question the two bags, but, the camera bag which was a Tamrac Adventurer 9 backpack only had camera gear in it - 2 bodies 3 lenses, a flash plus all the bits and pieces like filters and spare batteries and chargers. That way I can always claim that its only camera gear and should be allowed - and it was . The secret is make it look like what it is - camera gear.

Where this principle will falls down is if you plan to use any light aircraft where the rules are all thrown out and you allowed virtually nothing. My wife did some domestic flights in Africa and the weight limits were outrageous - 19kg all up . My camera bag weighs nearly this much when fully loaded for bear.