The texture files the game uses for the nude bodies are named "(Class Prefix)_BD_N_00.dds" and the default lingerie textures included in ShadowX2X's nude mod are named "(Class Prefix)_PT_N_01.dds". If, for example, you make copies of the altered DE_PT_N_01.dds, DE_PT_N_01_NR.dds, and DE_PT_N_01_SP.dds files and change the PT_N_01 in their names to BD_N_00, then the Defender will look the same with the default underwear unsealed and removed as she would with the altered default underwear.