You can do it, but it’s not supported or recommended. You will be ghosted if you try this on the Advanced ATC server because you cannot communicate with ATC outside the starting region and do not appear correctly on the map. Which causes traffic problems, so just don’t please. If you must try this, do so at your own risk on the Free Flight server only. Remember the act of flying beyond any regions boundary is not supported. If this becomes a problem we will simply close the hole that is making it possible to begin with.