If you're looking for the path of least resistance/shortest time, then you just need to add database access to the things you're already using.

So, yes, just add DBI to CGI and HTML::Template, and you've got all the basics in place.

I've built fairly large and complex websites with just those three elements.

Of course it wouldn't be a bad idea to use Catalyst or CGI::Application, but the P of Least R is just to add one more module to your kit and get to work. You can always add those frameworks later, and you'll understand what they're doing better when you do.