Creating a total customised Header, Main Menu, Top Section and Footer

Hi is it possible with enfold to crew a site where i build my header, main menu, top section and footer using the theme page template “no header or footer”

In theory and with the tools i know visually it is very much possible. What my concern is when it comes to how google will read the source code and what might not be there that should be there for google to pick up that it is the header region of my site and the difference there will be from a traditional header using <header></header> etc and what normally would be written in the first 50 lines of the home page or page.

My 1st question is would there be a whole structure that is missing when the header is built this way and will it then ruin googles, bings, yahoos! or any other browsers opinion of my site, with that resulting in poor to no page1one on search engines rankings being possible when SEO optimising of the site???

My 2nd and most important question is would you recommend me not to build that part of the site this way because its stupid?