Make a company which connects companies and individuals with other individuals or companies who will write wikipedia articles for cash.
This sounds bad, but isn't too different from what happens now. If a company wants something changed they have to convince other (hopefully unassociated) people to write about the thing or change the thing they want changed. This happens all the time. I've seen it personally at some companies that I've worked at. The difference is that this company would formalize the transfer for a modest intermediary fee.
I'm not sure if this idea is morally correct or even would follow Wikipedia's COI rules, however it would probably make a lot of cash. The company itself would be morally in the grey area in my opinion as it simply connects unscrupulous people with other unscrupulous people. It doesn't inherently do anything bad, but it does allow bad things. Like how Napster can be used for good purposes, but everybody pretty much just stole music.