All interesting and thanks for everyone's thoughts. Today I am leaning towards the 24-105 + 17-40 + "Shorty 40" (for low light situations) in my Retrospective bag. I love my 70-200 but on past trips, based on EXIF on LR, rarely used it (this is my first trip with the 5D - my old kit was a crop with 15-85 + 10-22 + 70-200). I did use the WA zoom for interiors. I know that I'll miss whatever I leave home, but I've lugged a heavier kit in temps over 100F and it is no fun.
Since you're trying to keep weight down, it seems a bit odd to me to take two overlapping f/4 zooms. How often did you use the 17-40 wider than 24? If seldom, leave it behind. If you hardly ever use the 70-200 because you hardly ever go beyond 70mm (as opposed to because you seldom go beyond 105mm), what about taking 17-40 + 50mm prime?
The advantage of the 17-40 is that it is weather sealed and does wide as wel as 'normal', a real asset if changing lenses is a no-no (ie dusty or wet environment). This is why I carry both the 17-40 and 24-105. Depending on the conditions I often pick a lens and stick with it during the rest of the day.
5D3, 5D2, Sony α6000, G16 | EF: SY14/2.8, V20/3.5, 24/2.8, 35/2, Ʃ35/1.4, 50/1.8, Ʃ50/1.4 EX, 100L Macro, 17-40L, 24-105L, 70-200/2.8L IS II, 1.4x II, 2.0x III, 70-300L, T28-300 Di VC PZD | E: SY12/2, 35/1.8 OSS, 16-70 ZA OSS, 55-210 OSS, SY300/6.3 ED UMC CS, Metabones SB | Vintage FD & FL glass.