perldoc base reveals that multiple inheritance of fields is not supported.

That's ok, multiple inheritance requires detailed knowledge of the parent classes and great caution. So much that most perlers discourage its use.

I say go for it, but you'll need to forget the convenience of base.pm and friends and work it up from scratch. You'll gain a sure knowledge of the properties of your new class.

Update: From following my links above, it appears that recent perl now supports multiple inheritance with base.pm. The denial of that was from my perl 5.8.4, and I suspect you're using an older version as well. If you hit resistance to updating perl, my advice still stands.