How were you planning to implement the Fan?
Always on - probably easiest to split the power supply going to the pi rather than trying to gain access to obstructed GPIO pins.
Fan controlled by Pi - Split the access to the GPIO pins, this can be done using a GPIO splitter such as This
or by adding extra connectors into a ribbon cable
(you would need one female
connector to attach to the Pi GPIO pins, one male
connector to attach to the screen and then your choice of male or female for additional GPIO pins).
You will have to know which pins the Display is using as these won't be available for controlling anything else.