Oh, I enjoy thinking about it too ... it's coding it that's a pain in the *ss. 8-)
Along these lines though: I considered just writing a "compiler" that would batch do what you say: Filter out what I want into a separate production tree. Keep both trees and muck with @INC at start-up to point to one or the other. I don't currently have any special install type interface, so the work there is formalizing code installation. I should be doing that anyway, but of the 3 Perl virtues, I have an extra dose of Laziness.