I'm just about to start coding, but I'm excited enough about where I'm going that I figured I'd mention it.
I've decided to use a template toolkit (Happens to be HTML::Template, but that doesn't really matter.) to generate my dynamic data. Then, to get the static side of my reports ready to merge with my dynamic data, I'm looking at PDF::Reuse. That seems really good for my particular purposes, 'cause I can off-load the form generation to any third party who's willing to help. I convert their output (from any app) to PDF, plop my template-generated data on top using XY co-ordinates, and it's off to the races...
Don't know much about your details, but maybe this approach will be at least worth checking out.