Naked Girls at the Beach, some boob physics, nice pussy, boobs look bad. Topless Girls at the Beach, maybe other areas.
(There are also various nude skins for MP which can also be used in SP via using a trainer to play as that skin, feel free to browse those at GTA-mods.) I am featuring three nude mods for the game. Best place for GTA V Mods (Avoid the Nexus for this game, although it's great for most other games, the GTA V mods are largely outdated)