I think I should post the finished code here (...) What do you think?

Definitely. Making working sample snippets available to the public is always a goog thing, especially if the regular documentation is terse.

Also, you might want to submit a (friendly worded) feature request against PDF::Table, saying it would have been nice to have something like the missing 'cell_render_hook' to solve your problem (just link to this thread). In case the author agrees, we might see this functionality in an upcoming release...