Two thoughts:
- Operate as a lottery in a way, choose the winner(s) at certain parts of the day - say 6 am, 12 pm, 6 pm, 12 am or at a time that has more user traffic. Maybe have the percentage awarded be dependent on who bid the most up to a certain point? This could be gamed by the user with more steem but maybe some way of delegating voting power/rewards can be discussed.
- Offer a resteem feature as well, that way it would increase interactions for @randowhale and increase the visibility of participants posts, maybe offsetting not getting selected for the payout so it's not a total loss .
Easier said than done and after writing those ideas I already started seeing how they could be used unfairly - but who knows, what does everyone think?