The use case, many servers (1000) in a commercial environment. We have no direct access to the internet, and we have to use a vetted source for CPAN on a local fileshare, not public repos via FTP or HTTP. We could bring up a local HTTP repo, but would prefer to use fileshare

local::lib doesn't help there. It's used to locate installed modules; it's not a means of fetching uninstalled distributions. You want minicpan to create a local CPAN.

Note: I avoid local::lib because it uses the INSTALL_BASE scheme which causes problems when you upgrade your Perl. PREFIX + LIB is the way to go. Or you can do what I do and install Perl itself locally using perlbrew.