Is there a way to prevent the TinyMCE editor from chaning the raw html you've inputed? I'm trying to use font awesome icons within list elements and it's erasing the markup on save. I don't want it to gut check my html, just accept whatever I put in the editor.
Maybe you can create your own PropertyData for the XHtmlString property. I'm not sure if this will work, but you need to decorate your property with the BackingType attribute that needs your Custom PropertyData as parameter. The PropertyData will be called when the value of your property is saved or loaded from the database.
Example of how you can use a custom PropertyData: http://www.patrickvankleef.com/2015/02/03/episerver-custom-property-in-dojo/