Personally, I got a few PMs in which I was offered just something like this - but that idea was never acceptable to me, ethically it is something I would put in the category of buying/selling BTT accounts. This service may be of interest to those who have a large number of alt accounts (which is not prohibited), but it is certainly forbidden to have more than one account in a particular signature campaign.
for campaigns that gives you good return, you must have a senior account with 250 merits and it difficult to get 250 merits these days.
Set yourself a goal, 20-25 merits each month and in a year you will have enough to become a member with a Senior rank. If you can really write quality posts for others, why not do it for yourself?