I have a Hensley and use a coupler lock similar to this one:
Keeps the hitch locked to the trailer, about all you can do without taking it off the TT every time you park. Good news is that it's so heavy and awkward that it's very difficult for somebody to just walk off with it.
Another deterrent is to use cotter pins instead of hitch clips to attach the struts, spring bars, etc. After the hitch comes out of the coupler, it has to be disconnected from all the other hardware also to be portable. Honestly the hitch head by itself isn't worth much if you have to buy the strut bars, spring bars, brackets, stinger assembly, and all the rest of the parts to make it usable.