What if, instead of completely closing it off, you made Epstein elimination island accessible to everyone but they have to pay the travel fee and time? So there's slightly more inconvenience for outside mercs and medics.
Participants could be free to travel to and from island also but you don't have full inventory access Your team has a storage vault on EI, that you have to bring stuff to before the kick off.
I'm not even sure I like that idea 😆 just spit balling