Yes, it is permissible for a man to have intercourse with his wife without a cover, and it is also permissible to have intercourse in the bathroom, but that means that he will be going against the Sunnah by not mentioning Allaah beforehand. Perhaps you know that the Sunnah, when a man wants to have intercourse with his wife, is to say, “Bismillaah, Allaahumma jannibna al-Shaytaana wa jannib al-Shaytaana ma razaqtana (In the name of Allaah, O Allaah, keep the Shaytaan away from us and keep the Shaytaan away from that with which You may bless us).” Perhaps you also know that it is not right to mention the name of Allaah in places where you relieve yourself, so how can the one who has intercourse in the bathroom recite this dhikr? Unless he is going to go out, recite this dhikr and then go back in.