I thought the blockchain has no mechanic for this, i.e. the payment window is set to 7 days.
What does Steem Bounty do? Do they claim the upvote in the background and then redistribute? Because if it relies on Steem, this can only be a workaround hack since the blockchain has the 7 days window. Anything else is pretty much just a hack.
Read the linked post. They create a comment under the post and upvote the comment instead of the post. (Which cannot be upvoted).