Aside from the fact that it would be a monumental task to replace rt.cpan.org (in dealing with spam from unauthenticated email submissions alone), you can't de facto replace rt.cpan.org without providing PAUSE-account authority to the uploaders to manage their queues. rt.cpan.org currently just has you provide your PAUSE credentials directly, which isn't feasible for new sites - a PAUSE OAuth interface would be very useful for initiatives like this...