I did it last year through Death Valley. I had an Engel25? and my usual Engel 45. The Smaller one carried Ice Cream and I set the temp most of the way down. It ran essentially all the time, and didn't cycle that much.
What I learned, is that if you stopped in the early afternoon, and let them both run, by the following morning, the starter cranked really really slow, suggesting significant drain. One morning after the warmest camp, it wouldn't start and I had to flip over to my back up battery.
That was with a good 75 amp-hour deep cycle battery also serving as my starting battery.
With a dual battery, you'll be good to go, with one battery, I'd start up and idle for 15-30 minutes before going to bed.
It was great having Ice Cream on day 5.