When we camp or rv park I've never used one. However if were going to be gone several days and leave the 5th wheel in its shed at home I keep a 12" long piece of 3/8" grade 70 transport chain and a big padlock around the king pin
"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers
'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach '97 Park Avanue 28' 5er 11200 two slides
I use this one King Pin Lock but although it works fine, I don't like that you have to keep turning the key to lock/unlock it. Kind of a pain in the neck.
I don't use anything and then again I don't park in areas that are prone to theft. I think there is a slim chance that someone says " Hey lets go by this location, maybe there's a fifth wheel we can steal".
Have Fiver will travel with little or no notice at all. I do need to stop at rest areas now and then:)