This simple OCMOD will add a checkbox above each of the description editors, once checked and saved the Summernote editor will be disabled. This allows you to freely add in HTML, CSS and JavaScript without the editor removing or reformatting it.
For OC 3.0.3.6 there is some issue with twig templates not getting the mods applied, there is a free mod that fixes this in the marketplace. Install that FIRST then this and its fine.