Gird tie equipment is designed to avoid creating self-powered "islands" when the connection to the main grid is down. This is exactly what you propose to do.
To use grid-tie equipment in its normal mode at both ends you'll need some extra equipment, such as a piece of rotating machinery, to provide a solid, constant-frequency, essentially constant voltage on your "grid" for the inverters to push power at and the charging mode to pull power from. This will probably have to be able to handle including sourcing and sinking - considerably more power than either the inverter or the wind genny, to avoid going off-frequency and triggering the island detection of the grid-tie inverter, causing it to cut off. So it's not a particularly practical approach.
If the inverter at the battery site has a configuration that allows you to set it to "electrocute the lineman" mode you can do it. B-( I'm unaware of a "make an island - I really mean it" mode. But you could talk to the manufacturer of your inverter(s) to see if they provide it.
dbcollins seems to be saying that Outback inverters allow this. (Or perhaps they will let you run the "house side" of the grid-connect out to the mill and transfer the excess power backfed from the genny into the battery.) In your place I'd check with tech support at Outback on whether it's possible and how to configure it, before buying the equipment. This is not something I'd expect them to make it easy to do, for fear of having it done when it's not intended and ending up with dead electrical workers and major product liability.
