Why would you want to? Be in regs (don't have a choice anyways) and be happy to be closer to the USAF and wear the sage fleece!
I do LOVE my black fleece but black is for the corporate uniforms. If you can wear the USAF style unis (as a cadet again, have to be in regs anyways. I believe even if you're over 18, I'd have to look in 39-1 on that, been a few months since I looked at it) just wear green.