You simply divide content and display, for example you leave the text in a .txt file and read and print it within the php. Now, if there is avariable for printable set, don't display the html around...
I did a script that does stuff like that automatically and will soon release it when I debugged some minor problems, you can see a running version of it at http://www.onlinetools.org/articles/stretchypages.php...
Another idea is to take a new php script that simply cuts out all the HTML of the page while displaying, you can do that by reading the content of the document into a variable and then doing a $var=strip_tags($var) or for older php versions
$var = ereg_replace('<([>]|\n)*>', '', $var);
cheers
Chris