Vieques Air Link and Flamenco are not doing on-demand flights anymore, only schedule, that's the reason they want ATP pilots.
Air America require IFR minimums, a friend is working there, and yes, the owner is not very friendly.
You can try M&N, Roblex and Air Cargo Carriers at SJU, cargo operators with short-360, sometimes they need f/o.
Seaborne is not hiring at the moment.
Isla Grande have many schools you can try, there is always looking for cfi.