This is the kind of trick you see the pros throwing in between their huge tricks and think to yourself, "I can do that." Then you try it and get worked. Well, maybe it's time to try it again but now with a few tips that will help you make it happen.
One of the golden rules to bunny hop 180s is to make sure you are flat when you take off. If you jump while you are still on edge, you will be thrown off axis and bust ass. The next thing you want to think of is keeping some tension on the rope. Most people tend to let the handle get way out when they start to let go with one hand. Slack = bad!
So now you've cut out, gone flat and jumped up. Keep your head up and turn it in the direction you are going to spin. Also, give a slight pull to the small of your back as you are spinning around. This will keep you on a slight edge away from the boat so you don't get pulled in toward the boat. When you get bored with that, try adding another 180 to it and making it a 360.