Hitch Lock

I use a simple one- when the camper is in storage or parked on the road in front of my house. I never use it while camping because to steal my camper, they have to break in, bring all 4 slides in, bring the awning in, move random stuff from under the camper, disconnect water, sewer and electric. If they're doing all of that- they deserve it. :)

http://www.learntorv.com/2013/12/fifth-wheel-security-king-pin-lock.html