Sometimes the government subsidizes a fight, which could make up for the difference. I doubt it'll it work for the Philippines though.
There an interesting video here on boxingscene with Bob Arum talking about having a Pac fight in Macau. The time zone difference wouldn't matter because they could have the fight at any time in Macau because gamblers don't care apparently. He mentioned that when UFC came to Macau, gambling revenue that day increased by $30 million (can't remember the exact figure) more than normal. The problem with having a fight there though is that it's harder to promote a fight in the US if it doesn't take place there. Thus PPV buys in the US suffer.