As a frequent traveler to SE Asia, alot of thought has gone into how I should carry my gear, clothes and essential travel items. I use only 'one major bag' and one carry on.
I am sure other bags 'may work', but lately I have been using the Akone 144, it's big, but does the job.
Use TSA locks all around (one on each side pocket to hold the fins and other gear, and one on the main hold), I also use the protective cover they send with it, although mine is now 'very used' and full of holes (sure keeps the bag like new). Along with my dive gear, I have managed to stuff all my clothes, and gear into (or on the top and sides) the main compartment. I use 'compression bags' for my clothes as well.
I would have to agree with the others, I 'carry on' my regulator, computer, camera and other 'must haves' with me in a large back pack/roller.
By the time this bag is full, ( I have even carried several kilos of soft weight) it can weigh at or about 32 kgs. which is maximum for 'transpacific' (check with your airline first), so I have had no charges there. Where I get burned is the local flights between SE Asia countries and especially 'inter island' (alot in the Philippines).
Lastly I buy DAN gear insurance, they cover everything including theft, as long as you have a police report. Usually the bag is 'so heavy' you would have to be Arnold Schwarzenegger to move it, so I don't worry about someone running off with it.
The only problem I have had with the Akona gear is this last trip, I 'really jammed it full' and while zipping it up, I tore the stitching on the outside fin pockets ever so slightly, but otherwise the Akona gear is 'bullet proof'!