I'm doing invasion stripes in a different way on my P-47 Thunderbolt. Instead of spraypainting the stripes, I've decided to kick it up another notch by hand brushing the stripes white and black. Since most invasion stripes were never spray painted on but were done by hand.
Also, my thought of using flat white and flat black gave me an impression the stripes would look too new during combat.
Instead, I'm using Vallejo Off White and Floquil's Weathered Black to give it a bit of both a sort of hand brushed look and a subtled beaten, weathered look as well.