Usually in deserts and nearby areas rivers and streams are never permanent, even when outside the strict arid area of the desert to a place that has more precipitation.
My suggestion for the area would be for all streams to be non-permanence, as waterway=stream. You can also draw some isolated, small endorrheic basins directly in the desert area around oasis and salt lakes. Drowning a whole basin that drains into the sea in a place like that tends to be unrealistic, apart from the edges of the desert.
Can't wait to see how this develops! I'm busy enough with my own country to even consider owning a state, but I'm very interested to see how the northwest of the country develops right next to my country.