... life is much easier when external dependencies are minimized.

What external dependencies? In an earlier link in this thread, you rejected consideration of a function like  List::MoreUtils::natatime because it was part of a module on CPAN. But I don't understand what difference that makes. Just Use the Source, Luke! Whether  natatime is really appropriate to the problem at hand is another question, but I just checked and as toolic pointed out, it's about half a dozen lines of pure-Perl, standalone code; if you need it, just steal it for Heaven's sake, that's what it's there for! (Although an acknowledgement of provenance is always a nice touch.) A simple cut-and-paste and you're done. And there's a ton more code where that came from.