El Mirage dry lake is kinda short. The Alvord Desert -- in southern Oregon -- is fairly long, but like other dry lakes, is subject
to flooding. A competition there would likely require a fair amount of effort in preparing a track (not so much by dragging,
but more by fodding and laying out some mile markers). This was done quite a few times when the North American Eagle
was running there (not after 2019). It's a pretty good dirt surface, and relatively non-corrosive. I don't know how much
traction it provides, compared to salt, but the extra length probably would at least help compensate. About 9 miles was usually available when not too wet. Unfortunately, it's pretty isolated. There's not much of anything useful within a few miles of that place.