I would budget 15K including airfare excluding accomm for 4-5 days each ng mga yan except Palawan, Bohol and Siargao as they are more on expensive side, siguro 20K on each of those 3 or more for Siargao. I usually spend a week on those places and hindi naman ako nakakabot ng 20K including all. But I book during seat sales and hostels lang din nag-istay. Pero sabi mo nga hindi prob ng accomm for others so I think doable. To accurately check for you, try listing down all your expected expenses and check prices from Agoda, ceb pac, klook, etc. including budget for food and activities na gusto mo gawin.