Use Template Toolkit for simple .html files?

I currently have a site that uses the Perl and Template Toolkit (using the module Template) for pages that require calculation and / or access to the database, but regular HTML files for the rest of the pages. However, I found that it would be nice if I had access to good quality templates even for “simple HTML” pages, if only for convenience “including” standard headers and footers, etc.

What is the easiest way to submit this with the least amount of crashes on the current site? (i.e. I would prefer not to change all the file names and links).