I just purchased a tandem axle "Long" brand trailer for my 21' Aquasport. It doesn't have the flip-down locking lever like most hitches, but instead has the turn knob style that you use to lock the hitch onto the ball. I would like to put some type of anti-theft lock on this, preferably something I could use both when it is hooked to my vehicle and when it is unhooked and parked. I know that you can get those nifty little bars that slide and lock through the flip-down lever on the trailer hitch and also through the receiver pin hole on the vehicle. Is there anything like this for the turn knob? Thanks!