You might need to try something entirely different but you might also just need to, for example, use the Liberator to help your partner angle their hips a little more. He could stand while she kneels in front of him using one hand to hold up the belly if need be or he could stand while she lays on her back with her head dangling off the edge of the bed wit her mouth open to him. If you're in agreement and have pre-negotiated things, that's a little different.