estimate for the 2 stair rule. you dont even have to do that, enough snow that will kick you up enough to heighten your pop a little bit is all you need.
think of how much better at rails you would become if you acclimate yourself to a tiny jump, no matter what the rail. eventually, you will develop the same balance on a big jump, only on a small jump.
after a while, you will be accustomed to smaller jumps, and won't notice the difference.