About 1995, I converted a sixteen-foot heavy-truck utility-bed service-body frame to an enclosed camper-trailer.
For the bumper-pull hitch on the trailer, I fabricated a captive sliding tube of the same two-inch thick-wall steel used for the rear receiver hitch on most bumper-pull pick-up trucks and vans in the three-quarter ton and stouter ratings.
Picture the 'V' of the two frame rails at the front of a trailer.
They meet at the 'tow' end of the travel-trailer.
Usually, welded to them is the triangular combo bracket for the ball capture and the landing gear.
I thought that standardized contraption was too easy to attach to a standardized hitch on the back of any suitable-sized vehicle... and grow legs without my consent.
Instead, I fabricated a receiver on the front of my trailer identical to the receiver on the rear of my towing truck.
Instead of a traditional two-inch ball at the rear of my truck, I fabricated a pintle hitch rated someplace in the neighborhood of fifteen ton.
(Of course, as we all know, that number far exceeds the tow-capacity of a Class 3 truck such as a Dodge 3500.)
At the front of my trailer, instead of the traditional ball capture and landing-gear triangle, I used thick-wall square tube the next size up from two-inch square tube.
The i.d. (inner dimension of the larger tube) matched the o.d. (outer dimension of the two-inch tube), allowing a slidable extendable removable hitch on the trailer.
This way, my ring (matched to the pintle hitch) can be slid in and held in-place with a standard hitch-pin.
Away from camp, I removed the hitch-pin, and slid out the ring on its two-inch tube.
Another two-inch tube -- blanked so nothing could be inserted -- was locked in the tube.
I got the idea on a trip through Baja.
Beach launching of small boats on trailers often requires the tow vehicle to be in the surf zone.
Some folks whacked off the standard triangle on the front of the boat-trailer, and replaced it with the tube-in-a-tube.
Using a much longer inside tube -- a standard two-inch thick-wall -- boaters could extend the inner tube out several feet so the truck avoided a salty soak.
Although I have no photographs of my rig, this is a similar concept.
On mine, for stability, I added a cross-member a couple feet aft of the ring.