As they do on more and more flights, the passenger plus their baggage should be weighed, so that the pax can be distributed correctly, and charged for. Average all pax ay say 100 kg.
Don't get me onto the subject of hand luggage which is mainly never touched during the flight. especially litres of inflammable alcohol. OK, if a pax has only hand luggage, include it, but if they have checked in bags, add the 7-10kg to the usual 23 kg, so say 30kg.