I have some ideas.
First, signature campaign managers are "supposed" to be the ones who ban people from campaigns.
Second, signature campaigns should pay people based on the quality of their posts (not on number of posts).
Third, payments shouldn't be made for signature campaigns if they adopt one of the following strategies:
Posts must be more than 75 characters.
Posts must be more than 3 sentences
They should add another one for pots being on topic with the OP.
Finally, users should NOT be paid based on rank, but on loyalty to the campaign.
Example: a user should have their payment increase by, say, 5% per payment.
Or, there could be fixed payment systems (that paymore than payment per post, that are more efficient)
I find it good to have a minimum amount of character and/or sentences!
After all, if your answer is too short, that means you add nothing to the thread. So that you shouldn't post at all.
That will limit spam, not only for sig campaign but for everything!
I like this idea a lot. But not the 3 sentences part cause sometimes you make just one super ultra fucking long sentence xD