these formulas are all pointless because you'll never know how fast you are going on skis, and they only work for tabletop jumps, and tabletop jumps dont usually have a completely horizontal kicker, there is transition in the angle and those formulas are designed to work only in ideal conditions ie, zero friction. so on top of all that you'd have to figure out the frictional coefficient of yourself to the air, and then find an equation to relate that to the projectile motion equations. all in all, just look where everyone else is starting for the jump, and then straight line.