setting up "areas"
Just educate your clients on use of heading tags found in the WYSIWYG editor...and tell them that to maintain the websites styling throughout (that you have it programming into the sites global styling)--to not assign any color or typefaces to the headings...unless they wish to.
All of my clients understand this--and if they are truly found of a certain color for the headings, have them contact you and you can change it in the headings globally so they will not have to assign different colors to the tags as they edit/update.
Having so many ssi in a page is typically not the most optimum way of doing things--break it to sections that they will require regular updating to.
Be sure that when you insert new content, you maintain page name for all areas of one page.
i.e. Page name: front page, content area: introduction are, Page name: front page, content area: contact information