I had this design problem a while back. The forces you get depend on how quickly you stop. The impact force could end up being infinite. Does failure occur? Some damage may occur in a collision, but not as much as the equations with infinite force predict.
Basically the only answer without spending $$$$$$$$$$$$$$$ is as ornerynorsk says. If you are worried about the load sliding off the forklift pallet, then do what I did. Go to you local warehouse supply store and pick up that "sandpaper tape" that is used to keep people and things from sliding on slippery floors. Increasing the coefficient of friction as part of the overdesign process was the best way.