I don't want my application to have any unneeded dependencies, log4net being one such dependency. As such, are there any thin third-party libraries or will I need to write my own?
Also, for those of you who need to have the "Why?" question answered, it comes down to the fact that I find 100k of binary code to conditionally write a single line of text to a file (my use case) to be a bit on the excessive side.
I'm not sure about third party products but you could resort to using the raw HTTP REST API.
https://developers.google.com/adsense/host/v4.1/ (this is for the AdSense Host API)
Google's documentation tends to hide it and they discourage using it in many places, mainly for security reasons they claim (ease of making mistakes with the JSON Web Tokens).