Why not use the Searchlight Airfield? You could repair the big hole in the runway and it'd work well as an airstrip. Does it need to be a completely separate world space?
first . well the searchlight airport is already used by the Enclave in the Mojave mod and so i dont want to start conflicts (althoug i currently use the mod as the base of my personal mod containing a US army outpost (edit the mod to some extend) )
second. the nellis base is way bigger and therefore more room to place certain buildings in and seperate it from the world so the story becomes and stays believable
third . well there are hundreds of reasons but mainly it can be made compatible with other ongoing mods or form the basis for other mods.
so my idea yes i would defintly say a new world cell (transport to and from the Mojave can be build in the mod to make it fit in the game world)