Having a reputable bounty manager is somehow needed but not necessary since this could increase the confidence of bounty participants to join on your campaigns. There's a lot of scam campaigns which can possibly affect your program if this is not been handle well by experience person. But its not mandatory but if you think your team is good enough and can handle the job then its fine you can run a campaign on your own but make sure you have an escrow to secure the funds of participants so that the community can tell that you are serious with the campaign you are running willing to pay everyone who made efforts on your marketing campaign.