EJECT... EJECT... EJECT!
I've been in a situation where my tyre's are both pointing skyward and I was backwards and upside down too. My recourse was to throw my body sideways and kick away from the bike. Also, I ride clipless but was able to accomplish this without much thinking. Torquing over to one side and kicking out will clear you from the bike (so it doesn't land on you). and yes, my CamelBak helped saved my spine too. Just remember to try and rotate as much as possible so you don't land directly on your shoulder.