Add custom font to MailChimp Design View Option

I have included a custom Webfont Asul in my MailChimp Code View post template using:

<link href='http://fonts.googleapis.com/css?family=Asul:400,700' rel='stylesheet' type='text/css'>

      

        
        
        
      

    

However, Asul is not showing in the design view in the font settings. The options only list standard fonts like Arial, Comic Sans, etc.

There is a cheat of sorts that works as fail-safe, taken from a 2010 article on the MailChimp blog. CSS below.

/** Failsafe restores Asul Font
* @tab Header
* @section preheader text
* @style Asul
*/
.Asul{ 
/*@editable*/font-family: 'Asul', Arial, sans-serif;
/*@editable*/color:#FFF;
/*@editable*/font-size:12pt;
background-color:transparent;
border:none;
}

      

        
        
        
      

    

However, this is not a satisfactory solution. The above code creates an inline style and places it inside a submenu. The average user will need to target their location. The image below shows this method.

Is there a way to make this custom font appear in the Design View dropdown list for selection instead of this nested approach? If so, how can I add it?