Well, all vehicles that don't contain a player or an AI commanded by a player (where player is leader to a group of AI), would be local to the server, yes.
You'd just need to play around with the value of _dist until the parachute dropped correctly, but the vehicle didn't look too far away from the chute.
I suspect, though I'm not sure, you might have to add a gamelogic inside the parachute in order for it to think it has a person inside so that it will fall properly. As I say, though, this might not be necessary, so don't bother unless you have problems. If you do this, you'd also want to remember to delete the gamelogic you created after it has hit the ground (at the end of Mandoble's script).
_parachutist = "logic" createVehicle [0,0,0];
_parachutist moveInDriver _mychute;