+ Bounty managers should be the ones to hold on to the project tokens and distribute after bounty ends
This one might be too risky. Because who knows if the bounty managers has any hidden agenda behind it. What if they took off with the participants' payment?
Sure, they could give the managers in charge to manage the distribution, only if that managers has a solid, and good reputation through and through.
They cannot just easily give access to bounty managers about such thing. Whether you get paid or not is another story.
The reputations is in stake here, if the manager will be allowed to hold the fund and serve as the escrow it should be a person who have a good and solid reputation. Developers who choose this way needs to consider that every bounty hunters are looking for good securities of receiving the share that they should have after the bounty period was over. In good faith, it can serve as an assurance that bounty participants will receive the bounty rewards once the manager already holding the funds.