Salinas doesn't get bitterly cold. Mid 20s is about it, right?  I think you've got good chances...
You can get thin vinyl sheets at the local hardware store. Throw in a few water containers, painted black, to soak and hold as much heat as possible. Drag out an electric heater if it gets too cold. A radiant heater, elevated and pointed down at the ground from a distance, might work quite well.