Well then it's pretty easy as long as you have backflipped on a trampoline before. I'm talking without a board though. Just make sure to lead with your head and not your shoulders. If you do then you'll start to twist. Also try to make sure your board leaves even off the jump too. It'll keep you from spinning too.
Im all for having fun, showing your tits and getting fucked up on a river float but it can be done without being a pig.