Accurate Customer Count

Whats the best way to get an Actual Accurate Customer Count? Ticket Count / Order Count is not (always) an accurate number of customers… example: if someone orders a Burger, thats One Customer, but if that paid person comes back and orders an Ice Cream, i dont want him counted. Or if two people spit a meal… i want it registered as Two People. What is the best way to track this?

Many people add a ticket tag for number of covers and report on the tag total.
In my V5 setup I have an automatic cover count based on number of meals (counting mains based on a product/item tag which also sets a order state and group for onscreen and printing), it prompts staff on ticket closing for number of covers with suggested value being a count of the number of mains. It can be overridden by changing the value at the prompt.
I even setup a secondary rule which if the tag is already set and ticket closing with a different number of mains it asks if it should be left, changed to new suggested value or user input new value option.
Also built into that rule is if you tell it to leave the current value or set a custom value it updates a state which disables the change suggestion on future closes.