I am curious, why would someone post bump a forum for two days only? A forum owner with a long term vision, wants continuous daily traffic over the duration of the forum's existance to attract attention from advertisers. The Google Analytics will reflect a spike and then normal traffic, so it would be of no use.
If I want to advertise on a site, I will ask for the sites performance reports over a longer period. So I would rather pay for posting over a period of a month to generate sustained traffic. You can place the payment in escrow or you can pay weekly to build trust. ^hmmmm^
Reason I don't do that is: 1) Main reason: I don't want to not have enough funds and end up getting a bad reputation. I would much rather play it safe and go day by day. 2) I do not want my forum to be a pay-to-post forum, but rather an active and quality forum
If you manage it properly, and you set a budget for the paid to post, you will not get a bad reputation. You also put hard limits on the amount of people who can join there, so you will never go over the budget. The community needs more opportunities for them to earn money/bitcoins from things like this.
It creates job opportunities and it also stimulates the whole system, because more people get introduced to micro payments for small jobs via Bitcoin. The advantage for your forum, will be constant traffic over a longer period.
Hope you will think about this, and start small. Once the traffic increased, you can pull out and advertisers can take over. ^smile^