The over-tanned look, for right or wrong, is currently the accepted and expected grooming for competitive Latin. I think it's stereotypical and rather silly, but so be it.
If you're going to go without tan, wear a costume that doesn't show as much skin. Basically, the more skin you show, the more people are going to think that you need a tan.
One look that people were experimenting with was wearing black fishnets with black Latin sandals, rather than going bare-legged and super-tanned. Maybe something like that can work for you. Think really classy and elegant rather than overtly sexy and wild.
Good luck! I, for one, love to see people being creative with their look, rather than doing what everyone expects them to do.