Get end date value of date unlimited values

So I have a node with a date field with unlimited values. It can either be Repeating Date = No or Yes depending on what would works best for the Rule.

The client wants the rule to send a Survey 1 hour after the end date/time. But with unlimited values for date, the rule chooses the end date/time of the first value because it can only be guaranteed that [node:field-visit-choice-1:0:value2] will be there.

Typically, the event is 1 day but it could be 2,3,4,5 days in some cases.

How would I variably get the end date of the last date entered, if there is more than 1 date? Thanks