I was able to mostly fix it by replacing "spidertron" with "spider-vehicle" in the source code. In one place I also had to simplify the condition to just check the vehicle name and nothing else.
Published my changes here: https://github.com/snakeru/Spiderissmo/
If you want to install it you need to create a "Spiderissimo" folder under your "mods" folder and have all files there. You'll have the following structure:
mods/some-other-mod.zip
mods/Spiderissimo/README.md
mods/Spiderissimo/...other files...