Have you read "Dark Money"? I liked it - I'll give "Democracy in Chains" a go too.
Koch funding at my alma (as I mentioned) was very contentious. There's an English department faculty member there who hosted a book club for a few months this fall semester, and I think they covered both books along with "Sons of Wichita". From what I understand, it went over about how you'd expect: very academically political, which is arguably the worst kind of political.