Well here's a few roles I think Vanessa Hessler could play as...
Poison Ivy is one. I was thinking let her wear a red wig or dye her hair red for the movie, I think Vanessa Hessler will make an excellent Poison Ivy- pretty, seductive and deadly that you would think twice before falling into temptation. I guess she's got the charm to play the villain. But if she's "too tall" for the part then maybe she should be Batgirl instead.
Perhaps as Aphrodite. After seeing her in Asterix, she could become Aphrodite after that.
Just my imagination and wishful thinking!