I "booked" 7 nights but told the CM I was only staying 6. At $50 a ticket for NWA to change, that extra day wasn't worth it. I did have to add a night of dining plan, but that's fine because we do a lot of 2 TS meals. Even with all of that we save several hundred. I was able to use Magical Express on our return day a day prior to our "official" check out date.
You can book just the 6 nights. That is what I have.