Back to the OP question... We've moored by the stern a couple of times in a cat. To do this we first moored by the stbd bow up close, and then using dock lines and some engine work transferred the load from the bow to the midships cleat, and then to the stern on one side, and then we hooked up the other side... ending up with one loop to port and one to starboard. This definitely takes some thinking through the operation in advance.

When moored by the stern the breeze and shade is heavenly in the afternoon, but you get your cockpit completely soaked if it rains. There's no place to hide.