Ok, I've got a plan:

Example:
I'll make a page "index.php" and include "news.php"
I'll then make the page "editnews.php" and use TinyMCE for the customer to edit the page.
Then I'll make "savenews.php", a script that read the post-information from "editnews.php", overwrites "news.php" and append-write to "backupnews.php"

Any pitfalls?