Few if any guests would mistake you for CMs in that outfit. One of the problems with people trying to cosplay or Disneybound or whatever you want to call it is that sometimes they try to make their outfit as authentic as possible, which makes mistaking them for actual CMs more possible.
The other problem with cosplay/Disneybounding is that the "play/bound" aspect of it can get out of hand. I'm not necessarily talking about girls spilling out of too tight costumes, I'm talking people running around in character, making a scene with little-to-no regard for others around them. You pretend you're a lost boy, and get in a sword fight with a friend dressed as a pirate, you're backing up, backing up, trip over someone in a wheelchair, boom, lawsuit. You dress up like Princess Sofia, your dress has too long a train, someone not paying attention to your shenanigans trips over it, boom, lawsuit. I remember maybe 7 or 8 years back, a guy who made a part-time living playing Santa Claus was asked to leave the MK. He wasn't dressed in full-blown Santa regalia, but his "casual clothes" could easily be misconstrued as "Santa's workshop clothes." Red shirt, suspenders, like he was about to build a train set. People started crowding around him, and it was starting to affect the flow of the park and the safety of other patrons who didn't get that he wasn't "on the clock" and tried to get a picture with Santa (for which he was being accommodating, which made crowds even larger).
KittyBubby, you seem pretty set on doing this, so I'm not going to tell you not to. But don't be naive about it, either. There could very well be consequences to your actions you might not like, but be prepared to accept them anyway. It's great that you talked to your Leaders about it - this means if they explicitly approved of your plans and it turns out they don't know what they're talking about, they'll get in trouble, too.