It be difficult to pull off his civilian attire as it looks like any other casual wear hence most people would think you weren't cosplaying.
It's safer to go with the military uniform.
But then again if you went with the civilian attire, you'll need something super obvious to tell everyone who you were.
When in doubt, just take the next small step.
With that next step take a deep breath. It calms the mind.
When the mind is calm you realize the best is still yet to come.