How closely can you control when perl.exe is launched from Inkscape? If it is just a matter of setting up the correct @INC, you can just launch it by setting up the process environment with PERL5INC=(?)/Inkscape/lib/perl. Alternatively you can launch (whatever) Perl.exe with -Mlib=(?)/Inkscape/lib/perl.
Of course, that Perl might be missing some modules, but at least Strawberry Perl comes with XML::LibXML included and you can easily distribute it with Inkscape or as a bundled package with your framework modules.