Lens choice for Havasu Falls?
I'll be there over Christmas as well - backpacking from the south rim to Bright Angel at the river for a night. I get out there every 2-3 years and will bring a 17, 24 and 70-200. We will have a full moon Dec 27-28th and it's pretty bright at those elevations (assuming clear skies of course) and makes nighttime shots managable (5 min f8 ISO200).
You might consider dropping the 24-105 in favor of food & water or an easier hike out but others might think that is the only lens you need to carry (eliminates the dreaded lens change on the trail)... for me the gap btw 24 & 70 mm isn't too significant so 40-70 gap seems very manageable.
Enjoy & Happy New Year!