Any of the 2 seater mounts will work. All you need to do is set up an IWT macro to your main toon and spam that and one slave will enter the mount the others will try to get in even if there is a passenger already and just "follow" the main. I was running 4 pallys in AV the other day on the Obsidium Nightwing mount. Works pretty well but nowhere as effective as /follow.