Hide/Mask URL using iRule

If you're only worried about that URI then a simple rule like this would suffice:

when HTTP_REQUEST { 
   if [HTTP::uri == "/"] { 
     HTTP::uri "/home/default.htm" 
   } 
 }

This simply checks the incoming URI. If it is "/" (i.e. top page of your site) then it silently rewrites the request to /home/default.htm" before passing it onto the server.