Welcome to the forum.
Hi, I could be wrong, but I don't think you can adjust the water heater on newer model Airstreams. As for being too hot, it depends on the temperature of the outside water coming in. And in your case, [Nevada] I bet it's fairly warm to begin with. Even in my home I have to turn my faucets farther to the hot side during the winter and more toward the cold side during the summer. In the cold icey campgrounds my trailer's shower has to be almost as hot as it will go. And in the hot areas my shower is turned very close to the cold side. Both of my sink faucets seem to be fairly normal, but the shower control is pretty sensitive.