If you really need it production ready in 6 months, of course you should use Perl 5. However, one alternative to all the suggestions made so far is to use the (not quite yet ready for production) Perl6::MetaModel which myself and a few others on the Pugs project are currently building.

It is basically an implementation of the Perl 6 object meta-model in Perl 5. It will eventually serve as the basis for the Perl 5 runtime when we complete the Perl 6 -> Perl 5 compiler. However, there is actually no reason you cannot use it outside of that compiler as a regular Perl 5 class builder. At the very least it makes it possible to design your Perl 6 classes in Perl 5, and be prepared for the shift to Perl 6, while still having runnable Perl 5 code.

Like I said, it is not ready for production, but it does have a good size test suite which has +90% code coverage (however, this stat is only useful for refactoring the metamodel itself as many corner cases surely need to be tested (and many too need to be coded)). Contributions to the test suite are very welcome, and contributions/comments and suggestion on the overall design are also welcome.