That's another interesting idea, @EclipseSin I think tried this with the old exploit but I don't know if anyone has tried with the new one on 5.5.2. It did work with the old one, but it had a very low success rate so it wasn't really worth the risk to be modifying files on the system.But your originally thoughts
Maybe inject an html file with ftp to the wii u file system?
It's been almost a year since this post, but the same instructions should work, it's contenthax for the browser. Also I can't advise playing in that area unless cbhc is installed.