How about starting an overlapping model where you implement ads along with the fundraiser and roll in ad revenue like you roll in monthlies?
Yes, it could be done. But again, we subject ourselves to the online ad market (advertising rates go up and down with the economy and sometimes tank completely) and there are no guarantees that they can sell enough ads for our account anyway. We also subject ourselves to the demands of our advertisers, put our forum at risk if we are competing with our sources for advertising revenue, puts more legal pressure on us, and lots of readers will simply take steps to avoid the ads altogether which will crimp us even further. Afraid we’ll end up having to do both or several combinations of all the above forever. Hoping we can just continue to keep it simple and remain non-commercial as we are.