You don't need hiring bonuses. You need to make this place a good place to work at. I've spent all 3 overnights within 1 mile of the airport. With limited food options and things to do.
Start making this a better place to work at and you won't have a problem with retention and hiring new people. Hey, maybe try following the contract for a change too.

Hey management. You listening?

Didn't think so.