I was going to go to my friend's halloween/birthday party in normal clothes and a nametag with a different name on it.
But the sign is a good idea.
Look on the bright side, when you start in infantry and you can retrain pretty much anywhere else if your CO lets you go.
It's not like if you go in as an electronics tech and you train in that and it becomes difficult to retrain you.
Yep, a three cent halloween costume.