Since IllumiNations is at 9 PM most of the year, you'll be fine. Note, however, that patio seating is only a request and not guaranteed. Depending on when you go, how busy the restaurant is, how many before you also requested a patio table the CMs at the podium may not be able to accommodate your request.
If you are seated indoors or at a patio table without a view, the R&C does have a viewing area adjacent to the patio that is exclusive to those dining at the restaurant. Just let your server know you want to go out to the viewing area and they will pace your meal accordingly.