As you have asked about it to live support and it is confirmed that it is an exclusive bitcointalk promotion, I would not comment about how it should be done as you have suggested it already.
I will talk about the reward and I have to agree that it will be better to have more users to win unless it will be a regular promotion that will be running every week or month.
By the way, I'm happy to see Bitsler is coming back with exclusive promo for bitcointalk and I hope it is just a restart then we will see much more exclusive promotions after.
As usual, I'd prefer to see promotion in a form of contest/competition where I need to compete with other participants by playing a game. but I'm not sure if I'll be able to do it at the moment or in the upcoming few weeks/months since I'm currently a bit off from gambling activity.