Also, I just wanted to say this as hopefully it will make you even more resolved to get out of there more quickly...
If your H is taking pics of strange women on the beach unbeknownst to them, then he is also capable of taking inappropriate pics of your kids' friends or girlfriends when they come to your house. If that isn't enough to scare you in itself, then also imagine if this does happen and it gets back to the girl herself, and then you and your H will have to deal with the parents of this girl.
In a case like your H, I doubt that a girl being underage will deter him from attempting to do something like this.
Please, I'm not trying to fluff up a scary scene just to get your attention...I'm actually also trying to help you realize you need to protect your kids and their friends. It is not only you that needs protection from him.