If I were you I'd call back and try to get an ADR for between 7:00pm and 7:30pm. I'd be very surprised if you were able to get a patio table with an 8:00pm ADR. When I was there solo in May (Illuminations also at 9:00pm), I had a 7:10pm ADR. When I checked in, I asked very nicely for a patio table and told the CM I would gladly wait for it. The CM said she would see what she could do, but that anyone with an PS of 7:00pm or later was going to be waiting to see Illuminations. Luckily I was able to get one on the second tier, right next to the steps. The entire time I was there, only one table got up and left. Everyone else out there was there before I arrived, many obviously through eating, but no one was giving those tables up. The waiters know you are there to view Illuminations and purposely serve you very slowly. Even if I hadn't planned to stay there to view Illuminations, I would have had no choice because my dessert didn't arrive until just as Illuminations was starting. I had been seated about 7:40pm, by the way. I would think that the chances of getting two tables out there would be even slimmer, but good luck.
We'll be there in Dec when Illuminations start at 9:30pm (because of the Candlelight Processional) and have an ADR for 7:50pm. I intend to try for a patio table again, but who knows if we'll get it. After Illuminations starts some people come from inside to view it. When I was there in May a guy came out and tried to stand on the steps to take pictures, but the CMs told him he had to move, he stepped back for a few moments, then went forward again to sit on the steps (again taking pictures). The CMs got him again. About this time, someone at the table next to me asked me something. I couldn't hear her, so moved over to the other side of the table. After we finished talking, I turned to move back to my seat and the guy had sat himself down in my seat. I said 'Excuse me, but I was sitting there and would like to finish my dessert if you don't mind'. He gave me a dirty look then grabbed my plate and handed it to me. I couldn't believe his gall. Granted I was sitting alone and wouldn't have minded sharing the table with him if he had asked, but he didn't ask and seemed annoyed when I said something. My waitress was standing just behind us leaning against the wall, saw what was happening, and came forward to ask him to move again. Which he finally did.