Coupler locks apparently give a false sense of security. You might want to review this thread, particularly Texas_Camper's post (number 2 in the thread).
http://www.trailmanorowners.com/foru...ead.php?t=4664
Incidentally, on my current TM with the swing-away tongue, it is not possible to pull both pins. Only one is removable. So I pull that one pin and fold the tongue WAY back. The strange appearance will at least confuse a thief, although I'm not sure it will stop a dedicated one.
Bill