I'd say the 4 hours penality should be reduced only to 30 minutes in case of docking. This harms trader way less than the whole 4 hours, but still keeps them from docking for a minute only to refill, then go on their way. InRp we could say this time is needed for minor repairs, or for waiting for the pirate to go away.
Regular PvP death could keep it's 4hr penality. My thoughts over here.