Wearing just leggings is no good because skin-tight clothing is considered no different from being naked. Actually, that’s the style now on college campuses and high schools, to wear skin tight leggings and a shirt that doesn’t extend down past the waist. So for all practical purposes, aside from the color of the leggings, people are seeing them naked.
It reminds me of the story of the charedi rabbi at the bus stop in Israel with the scantily and tightly-clad women. All the people looked at the rabbi to see how he would react. He simply handed the woman an apple. The woman said, “Why are you giving me an apple?” He said, “Chava didn’t know she was naked either until she ate an apple.” Of course, it’s not a real story, and the fruit wasn’t an apple…