I can think of a few places in Dwilight where that unit setting would be useful (D'Hara, for example), but I don't think it would get a ton of use on our current islands. If we had an "island" like the Philippines, where most of the regions were their own island and bunched together, I could see it being the top unit setting after regular army and police.
I'd go with Marine personally, they were a type of soldier that originally specialized in ship-to-ship and ship-to-ground fighting. I agree with GundamMerc that "raider" sounds like it should improve your looting, perhaps at the expense of fighting ability.
