What is the best, simplest, and easiest approach to having a rock solid, reasonably "standard" perl setup?
You should seriously consider simply using the pre-installed setup unless you have a specific reason not to. The out-of-the-box setup for every shipping version of OS X so far is about as "standard" as it gets, and it's pre-installed, so if 5.6.0 is sufficient for your needs, then you already have a solid, standard setup for literally no effort at all.
If you really and truly need 5.8.0 - and there are some good reasons you might, such as improved Unicode support - your best bet would be to get it from darwinports. Since you're already using that, it should be as simple as just installing another package.
sherm--
Heisenberg may have slept here.