The dynamic range in AC is so great that no film or sensor can capture it. As with any such situation the best approach is to avoid burning out the highlights. Expose for the highlights and let the shadows fall where they may.
You can also try some of the digital belending or shadow recovery techniques detailedon this site.
Bring a large clear plastic grabage bag or two to cover your camrra gear. There can be a contant "rain" of sand from the top of the canyon above if it's windy.