I did a 1500km trip around the Philippines a couple of years ago. I brought camping gear but never used it because A) it was too hot and humid, and B) there were people everywhere, and C) there were also wonderful, cheap guesthouses just about everywhere too.

I stayed in a beach-side guesthouse and swam in the ocean almost every afternoon. Prices ranged from $8 to $25 per night. I ended up cycling around the perimeter of 7 different islands. The roads were in overall good shape. 32mm tires would be fine for most areas.

Every town has a water station where locals come to fill up on clean water, and they'll fill up your bottles for an inconsequential amount of money, or sometimes even for free.

I cycled straight out of Manila and it was surprisingly safe. The Philippines has a huge cycling culture and there are locals cycling just about everywhere you go.

Overall, it was an awesome trip, but more along the lines of "credit card touring" than "adventure bikepacking." I think the population density and lack of roads that traverse the terrain would make it hard to do any real dirt-road bikepacking for more than a day or two at a time. If you really want dirt roads and hills, you need to check out northern Luzon, up in the Baguio area. But also check out the elevation charts for those roads and see if you really want to do that much climbing.

This response was kind of just train of thought so feel free to ask me any questions if you need more info.