i have encountered the problem of having the tails dig into the ground when i was first doing somersaults / handplant fronts.. you just have to commit an get your body all the way around, also its much easier to do with a softer ski.
for me learning with a soft ski really helped me get it down an then when i switched to stiffer skis i had no problems so i think it was just a commitment issue for me.. hope that helps a lil...