Oh, good question! I've noticed more and more people being (professional) transparent about their desire for links and giving more specific - polite - suggestions for where to link or what content may be good for it.
You mention your reports - when you send them out, do you include ways to link? Are there embedded links? If so, do they work consistently (random question, I know - I've run into issues where the hyperlink doesn't work so it's wasted).
What about adding a section, like: For additional information and resources, please share these links: widgets: URL; exec info: URL, etc.
I think a big part of it is approach. (I'm sure you know better than to point out that a site is linking to a competitor and complain to the site/author about that.) A follow-up message, like: great post, glad to see the report is of value, here's some additional resources that could be valuable to your audience (link, link) if you'd be interested in updating your post.
I've noticed more people approaching me with specifics like that, and they do better than those who are just trolling (literally will email me just asking for any links from my site to their content). Not that I think you'd troll - like I said, it's about approach.