Monetizing user generated content

Long time lurker; first post. I'm working on a pretty straightforward project, you can think of it as public Google Docs with no authentication required, aimed at providing a temporary place for people to collaborate or share links/media. I'm not trying to create a proper income or anything, it's just a hobby and would be neat if it paid for itself. I was evaluating the option of using an ad network that offers well-designed, unobtrusive ads, but I have concerns about adhering to content policies. Do I need to implement moderation so that I can prove I'm trying to disallow restricted content? Will ad networks reject me out of the gate because I don't control any of the content in this app? Are there other options for monetizing UGC that I should be considering? Thanks.