when you are just straight airing the wake, try to suck your back knee up a little bit. It will look better and make you land more even weighted.
https://www.youtube.com/watch?v=Ckkf840HZE4
This video helped me a ton. Those backrolls look pretty much perfect.
Frank
edit, also start trying grabs and 180s. They arent hard, but take time getting used too.