IMO, it would be best to just go as you are. Trying to make your skin fairer would make it seem to others that your own skin is not good enough to cosplay in. If you're really going to be bothered by accuracy, then I would say that you would just not cosplay the character. But cosplay is especially about having fun, so you should say 'fuggedaboutit' and just have fun! (I'm black and I'm gonna cosplay some of the palest people you've ever seen soon LOL) So I would say don't really worry about it.