I know an escrow has been suggested by members above but I would like to express my opinion also regarding this matter.

As a forum member, I've witnessed a lot of scams in the past run by newbie so I would also suggest to put the signature campaign budget in escrow to ensure payment of this campaign, or if possible hire a trusted manager to hold the funds and manage the campaign at the same time, it will be beneficial for all of us if we can avoid spam in the forum.