>Martin, the one that you posted from http://purdy.gatech.edu/wp-content/uploads/2012/07/2_line_wt.pdf -
>I don't see how I'm going to be able to get that same result with only one of the silhouettes of that through-hole being accented,
>it's not clear to me which one it would supposed to be so instead I'll probably do both of them.

I regret posting this as it just added confusion. I didn't look carefully. The example shows a subjective way thats difficult or impossible to put into some sort of rule.
I'm fine with your "border against background" method that gives me a rendering like this: