I want to create a user guideline thread to be pinned to the top of each forum but I keep getting the warning that it is too long.  How do I get around this without affecting regular posts?

Okay for anyone else wanting to use a longer user guidelines I was able to do this by going into my add.php file and at line 20 look for this HTMLForm::check('content', 1, 14000).  It was originally set at 4000 so I increased it to 14000 to allow me to create my user guidelines and than changed it back to the default. 

Another way is to create a smaller post and then open it up inside a text editor like notepad++ and make the changes there. The posts can be found inside the data>>topics folder.  You don't have to change the default character limit in add.php this way.