This isn't in the Sierra Nevada, but you can always head to Death Valley. There are no quotas or required permits. If the weather is hot, you head up higher into the mountain ranges that surround the desert. If the weather is cold, you had down lower toward the desert.
The good news and the bad news. The good news is that it is relatively flat along the desert floor, and you can pick out some sand dunes if you need more up and down. The bad news is that loose sand can be very difficult to walk in. That's why I prefer the mountain ranges. You can get by with very little shelter, right up until a sand storm blows in. Then you will want whatever you can lay your hands on.