It has been my experience lately that the airlines have started taking the valid onward ticket from the Philippines issue VERY seriously and are indeed verifying that onward tickets are valid. So whereas in the past I might have said just print one up for that purpose, these days it really does have to be valid. The jig is up on the ol' doctored printout trick. However AFIK any VALID onward ticket should work regardless of date so it should not need to be within 30 days.

In probably close to 60 or 70 entries to the Philippines I have never once been asked by Philippine immigration to show one, but the airlines are asking at check-in pretty much 100% of the time now if I'm on a one way ticket or a return ticket originating in the Philippines.