I just spent the last two days I Death Valley and the Mojave desert with my 2011 Silverado HY2. I also took the beast down Titus Canyon (20 miles down a narrow canyon with some steep climbs) - which is usually done a in shorter wheelbase 4x4. The truck is stock generally with a slight lift on the front (1/2 inch) using the Bilstien shocks. I have removed the air dam for the trip. I have about 600 lbs of gear in the truck.

Overall the truck did great. No issues with Hybrid or 4x4 system.

The one issue that did cause some grey hairs was cooling - particularly on steep grades at low speeds. At the worst point water temp was 238, trans 180 and 110 on the HV battery (all from Scangauge). This occurred when I stopped took some photos and left the truck running with the A/C on. After that I ran with the A/C off and things were ok. Outside temps in the mid 80s. Given the low speeds I was traveling at I am not too surprised about the high temps - this is really not what most pickups are designed to do.

I noticed similar temp issues to a lesser degree when driving through long areas of sand and rocks in Mojave Desert - but due to higher speed the temps were not as high.

The fix would seem to be a bigger cooling fan or lower on speed for the cooling fans.

 

Photos of Titus Canyon