I run a 80 gal 10 horse 2 stage. When painting with a siphon feed gun, a small air compressor just don`t have the volume. On small projects you well still have to wait for air build up.
If your painting planes, try a small detail HVLP gun instead , sprays at a lower pressure, less over spray. I used a Craftsman 6.0 horse 30 gal. with a detailed gun, worked o.k kinda. The small one`s throw a lot of moisture.
With the gun you have you need at lest 45lbs. pressure at a constant 7 cfm.