Ft. Wilderness Cabins at 7 month window in October (for Halloween)?

[JulieWent]

Are Ft. Wilderness cabins usually available at the seven month mark? We are BWV owners, but my brother and his wife do a huge Halloween display staying in their RV every year. We'd like to be able to be there for it, so I'm making reservations at the 11 month mark for BW but would like to change to the cabins when our 7 month comes up. I'm wondering if that will be possible. (We also thought we might change to Wilderness Lodge, but we're still thinking about it.)