make a BP with two *overlapping *triggers.
introduce two variables which determine which of the two triggers you are overlapping atm:
overlapFront
overlapBack
on the OverlapStart/OverlapEnd you toggle those two flags.
together with the OverlapEnd event and the flag you know if the event is relevant and therefore you know which side the player leaves:
if overlapFront == false and EventOverlapEnd(Back)
–> player left at back end
if overlapBack == false and EventOverlapEnd(Front)
–> player left at front end
if overlapFront == true and EventOverlapEnd(Back)
if overlapBack == true and EventOverlapEnd(Front)
–> player went from one trigger to the other, but didn’t leave the area yet