If you ever do the mario kart 8 stream, you can have a race with you, the fans who participate, and if you run short of people, you can still include random people. You can join a random party online and have your fans join you there.
That sounds overly complicated. I'd rather just fill any gaps with computers and leave it open for stragglers. I don't even know how all that works, I'd have to look into it.