so the idea would be to:
1) house current specs at packaging.python.org... basically a document tree that's organized by topic, not numbers and it's free of proposal rationales, historical discussion, and transition plans etc...

 

I can't make sense of how these links are a response to point #1?
I wrote the PEP summary page you're linking me too, so I'm aware of it  :  )
This summary page is *not* the Specs idea. 
Maybe a picture is worth a thousand words here.... and will require a draft PR against the PyPUG to make it clear to everyone 

 
2) keep using the PEP process for adjusting or adding to the specs

and assuming that approach, I raised a few "publishing" questions:
1) do we publish/render all supported versions of a certain spec, or just the latest
2) if we publish them all, then how?  do we maintain separate documents for distinct versions? if not, how do we do it?

Tagged [semver 3.0 (+1)] versions can be managed *individually* with readthedocs. 

sorry, I don't follow your point.