Be careful of counting on the cell phone for communication and GPS service. If out of 3G/4G range there are no maps on most phones. Bring a 'real' GPS and if possible pre-plan/preview your route on Google Maps or similar.

I've always been a believer in the utility of those giant orange plastic bags ... in the desert they can be slit open and used as flags ... or to provide shade.

Speaking of flags ... I might think it would help to have a very large bright "HELP NEEDED" banner. Does anyone make such a thing?

Not being a desert dweller I have to ask: Are insects a problem at night?