Just a few personal thoughts and observations.......
Buying a lot is fine but who does it revert to if it all goes wrong (not impossible)
no 50/50 over there = she gets the lot and you will probably have to buy it in her name anyway
you are a kanu with basically no rights there if it all goes wrong
In this respect i feel that the renting option is a safer bet
Renting a place is cheap anyway so why shell out all that money
Buying a lot is going to benefit WHO
The first golden rule of most of my ex pat friends in Dumaguete is no relatives allowed in
their property
Sounds harsh i know but there are good reasons for it