That is not a practical solution. It probably was someone on the island anyway, or who spends a lot of time on Caulker, who knew her, her mode of operandi, etc.
There is a small cadre of drifters who spend time on Caulker, Ambergis, etc, that, cracked up enough, are capable of this, no question.
I would think the perp on this is one in a small group of suspects. Don't be suprised that this will be solved.
There'll be two dates on your tombstone. All your friends will read 'em. All that really matters is that little dash between 'em.