This is a short one. If cron is an old friend, don’t futz around with weird Ruby. You know the pitfalls of cron (environment variables, long jobs without lock files). So write your crontab and check it into config/crontab.
I picked up the term “flintstoning” from my visit to Cambrian House. It’s the practice of substituting a little human work for functionality until there’s enough demand for the feature that it’s worth the coder time to implement. Let me give you an example.