I have had remarkable success growing coconut trees and cactus and periwinkle.
I know your where making a joke in that those things just grow here with out any attention, but their is some wisdom in that.
Why not plant things like the Mayan Chia for a green leaf vegie, it doesn't need much attention and grows wild on the island, or cocoplum.
Lots of salt tolerant vegies that survive here with out having to fight an uphill battle.