Please publish the full list of all available SkinParam options on the website and in the PDF documentation. It doesn't seem to be available anywhere.
I do a lot of customization to things on the diagram, like background colors, line colors, font sizes, font colors, etc. It's difficult to know what options are available to change.
The only reference I can find is this:
https://github.com/aklt/plantuml-syntax/blob/master/syntax/plantuml.vim#L117
But ideally, the documentation should contain examples or short descriptions of how each option works.