For overseas travel, I'd recommend a Bike Friday folder with the touring suitcase that trails behind it on its own wheels. I have done tours with one both in and out of my own country without a hitch. Just pack it up, fly to your destination, unpack and reassemble, and you can be ready to go riding straight from the destination airport in minutes. Least hassle, I think. S&S couplers on more conventional frames are also very smart, but the Fridays are still easier. I'm not sure I've packed quite 50 lbs on it, having never weighed my gear, but it was able to handle quite a lot more than one would think, including my rather recklessly riding it on rocky dirt paths completely loaded for camping (and without the suitcase) when I lived in California and did day tours through wine country to Annadel Park and Armstrong Redwoods Forest, etc. I also did 500 miles through Thailand without the suitcase and loaded up with tent, panniers, etc. No problems at all. It's really a wonderful ride too, very comfortable if you ask for the handlebars to be made a little taller than the saddle.

That said, it is not my preferred tourer for tours straight off my doorstep, where my custom beats it in every possible way. S&S might be the Goldilocks option between these two things.