@metasim said:

Success!
[...]

I hope someone else finds this useful. I'm glad I don't have to resort to a client/server type implementation and associated headaches.
Simeon

Hello,

I've taken the time to register in SketchEducation just to be able to thank you for this excellent tip. Thanks to you I've been able to succeed after many headaches with my .bundle Swig/CMake generated Ruby/Sketchup extension files causing segfaults every time I used "require" to load them.

Linking against the Sketchup 2016 embedded Ruby library solved the problems and now I can use the extension!!

It was extremely useful. Thank you very much!