Nakajima Ki-43 "Hayabusa" (Oscar) / Akeno Army Aviation School - 一式戦闘機 「隼」 / 明野陸軍飛行学校

Nakajima Ki-43 "Hayabusa" (Oscar) / Akeno Army Aviation School - 一式戦闘機 「隼」 / 明野陸軍飛行学校: A line up of Akeno "Hayabusa" warming up their engines just before take-off. They are all Model 2Koh early. The serial number of the falcon in the foreground is partially visible; "38" something. The one in the background has the Akeno school tail marking and the number "48" right above it. The wheel wells look unpainted.
Note their different camouflage patterns directly over the NMF surfaces. The falcon in the background has one overall top color while the one in the foreground has a "madara" (mottle) pattern. A rather young and touchy modeler (insisting on calling the plane "Busa"; similar to talking about "Lcons") recently asked about the best way to recreate this mottle effect on his 1/48 model. I would really like to hear your ideas and suggestions. Airbrush or brush? Free-hand or something else?
Feel free to comment.