You can get fairly good coverage with the airbrush. Depending on the model, you can get quite good coverage. Some have very fine nozzles for delicate work but much of what you will use is quite heavy coverage with the nozzle opened to a degree that suits your need. I’ve used it quite often to do large works on vehicles. I’ve often used the spray bombs with similar success. You can get good coverage on large works such as on vehicles or just large clayboards. I would suggest using the acrylic reduced if necessary which you can experiment with first. Try that first would be my advice.
Without doing any small detailing, I’d use spray bombs that you can get at a range of stores. You can get just as much detailing in that fashion without bothering with the airbrush at all. You might need to make paper masks that will give you just as much freedom as you would using the air brush.
I’ll give you a couple of examples that are mostly done freehand with the spray bombs using your own homemade masks to suit the occasion. There is still the option of touching up some of the detailing with a small brush.