Well, I've never done multi-page forms that maintained a state in Perl, but I have done a hell of a lot of Perl web programs with multiple pages, and I definitely understand the trouble you're going through.

Just an idea, but have you considered adding a link to the Add Contacts page from the Add Product page that pops up in a new window? If you give your users a popup window that they can use to put in contacts using your current Add Contact form, and they can do it WHILE they enter products. I'd consider it the same tactic as popping up a dialog box in a Windows application. Just an idea... There are several tricks you can apply interface-wise with web programs that I've learned over time and they have always helped me out of major coding sessions implementing a feature that could be reasonably duplicated by making the browser meet you half way and jump through a few hoops as well.