My PT-60 has 3.5" total on a 71" wing.
The book called for 4" on the sport wing and 6" on the trainer wing.
Since the 40 size has about 10" less wingspan, 5" seems huge.
If were doing it again, and I might, I'd probably reduce it to around 2" or so.
The PTs are so stable and forgiving they don't need a lot if you're using ailerons.