Tattoo Cover-Up

I am thinking of wearing a strapless dress for my upcoming September wedding. The only problem is that I have tattoos on both shoulders and don`t really want my tattoos to show up in photographs. I have seen tattoo cover-up kits advertised in bridal magazines and on the internet, but I`m a little concerned about their performance. Most specifically, I am afraid that they will fade or smear. The last thing I need is to be smearing concealer all over my future husband and guests!
Does anyone out there have any experience with these types of products? If so could you give them a review?
Thanks