Allison-powered Mustangs in USAAC pre-WW II markings with yellow wings and blu or OD fuselages? Perhaps some fuselage trim akin to that done on the P-26?
Turbofans can be beneficial in reducing noise and, with a mixer, thermal signature. TSSAM did a good job of mixing the core and fan flows for reduced thermal signature and the mixer had an LO coating for all aspects "Stealth".