It is well known that even if wheel clamps, and a hitch lock have been fitted, the thief still seems to be able to tow a trailer away. One way to protect this valuable asset is to lock it to the ground.
The Telescopic Hitch Post, consists of an outer steel tube, 800 mm in length, and an inner telescopic tube of 5 mm wall thickness, which is designed such that it cannot be removed, and is topped with a 50 mm tow ball. The outer tube is sunk into the ground, flush, and concreted to make it permanent. Since it cannot be dismantled once it is fixed in the ground, there is nothing to get lost.
Ideal extra protection on your drive or caravan / trailer storage facility.