It will vary from operator to operator based on whatever is written in their instrument of approval

You'll typically not find a formal limit - and the instrument is typically formal permission from CASA to operate with a passenger outside the aircraft. Most operators however limit it to 50 feet above water and 15 feet above land. Australian operators do not use the double hook methods of the Europeans - just a single belly attached cargo hook, winch arm attached cargo hook, or a winch arm attach fast roping speed block.