I saw something (think it was Guy Cribb or Ben Proffitt) that said to open up the straps such that you can twist in them and still touch your knee to the board. When I set mine up like this I have to kind of pivot my ankle and grasp with my toes a bit to stay in the straps if the board leaves the water.
I'm a mediocre jumper though, but so far haven't had a problem on the boards I've used this guideline on.