Personally I think it's too close. I did almost the exact timing with a friend in March. We had 7:35 BOG and our 7DMT (which is right by it) was 7:55 to 8:55, which gave us until 9:10 with the 15 minute "grace" period. We were just 2 adults and didn't lallygag at all. No appetizers and only waited a few people to see Beast (while anxiously watching the clock). We ordered dessert as soon as we could and asked for the check early. But still got to 7D around 9:05 and had to wait in line behind a lot of people while stressing we wouldn't get there by 9:10. Wishes wasn't until 10 so that wasn't an issue but no way we would have made it (although we probably would have seen some of the fireworks from the mine train!).
If this really is the only option, let your server know you're in a hurry. Ask for the check as soon as you're done ordering and ask to see/get desserts while still eating the main course (they bring a dessert cart around). Know what you want from the menu before going in. Be prepared not to meet with Beast if the line is long. And plan to watch Wishes from right outside BOG (by the sign is a great place that has audio and gives you a 360 view of the fireworks on both sides of you). I would not expect to make it back to Main St. to watch. If all of this sounds too stressful, I'd move something.
One suggestion if dinner does take too long - since there is the 15 minute grace period, maybe watch Wishes from where I suggest at 8 and as soon as it's over around 8:15-20 jump in the FPP line for 7D.