I'm wondering if I need to wear a slip with my gown. My gown is a mermaid silhoutte with heavy beading all over and lace at the bottom. I never checked to see if you could see through it. And I don't need a slip for the control top as the gown is pretty body-hugging. I've looked around and can't really find a thin, silky-like slip that would work. Is the slip really necessary?