I think I maybe don't understand what you are trying to do.
I thought what you meant was that you have a general set of InfoPath controls, data structure and code that you want to be able to reuse in multiple templates. Since you need code, template parts appear to not be an option for you. I was suggesting creating a baseline template and using it as a starting point for each new project. But it appears I'm continuing to misunderstand what you are trying to accomplish.