If you can't get a room, I suggest an off-site hotel. We did the same thing our last trip, changing our flight to Friday night instead of Saturday, and it worked great! We stayed near the airport and had a free shuttle to the hotel. On Sat, we got free breakfast at the hotel and just took a Lyft to Disney (lots faster then Magical Express, and less $ than taking a Lyft from the airport) and were at MK shortly after park opening. I've seen some really good off-site hotel prices from Undercover Tourist. I booked our extra night through Southwest and got lots of SW points.