Trip of a lifetime, you say? Speaks for itself then -
Canon 24-70 f/2.8 L USM
Canon 70-200 f/2.8 L IS USM
1.4 and 2x converters.
Two fastest primes in you favorite length that you can afford.
Whether you have quality lenses in your bag or not, this will not stop it being taken off you. A 2000 dollar bag is as much an attraction as a 4000 dollar one, and these guys probably wont know the difference anyway. Be streetwise, stay with a crowdand travel safe and carefully. Your instincts in these countries are your best friends, listen to them. Traveling light doesnt mean you wonthave your camera and one lens taken off youifits going to happen. Just means you wont have the right equipment for that lifetime trip. Take what you need and like I say, just be wise about where you go. Take a pocket camera for certain city streets and leavethe restin the hotelsafe or wherever.