Doable as a very quick winter trip, not a major time commitment
Driving not needed for coastal areas around PN Huatulco and resorts
Non-birders happy to join for relaxing beaches, snorkeling, and resorts
Concerns
How is the driving on the road to Pluma Hidalgo? Road condition? Amount of traffic, and behavior of drivers? Some reports that the road is hairy to drive, but doable. See Facebook thread, and trip reports from Hornsveld, and Maurice et al., below.
Is it possible/reasonable to get a taxi or colectivo to and from Pluma Hidalgo (and San José del Pacifico)?
Lodging in Pluma Hidalgo?
Finca Don Gabriel ~$70 per night, recommended by several in Facebook thread below.
Relatively few trip reports from independent travelers, though quite a few from group tours. It does seem to get birded independently, just few written reports to draw information from.